Matt Godbolt: Hey Ben.
Ben Rady: Hey Matt.
Matt Godbolt: So you were talking to us the other day and by us, I mean, the folks at work about one of your, your past times, which isn't really very programming related, but somehow, because you are, you, you were able to bend it to fit a group of technical people. So I figured we should take the opportunity to, to ask you on this podcast about that so that you can, you know, um, give more people the, this, uh, a window into the world that you describe. So do you wanna talk about it?
Ben Rady: Well, this is definitely, yeah, this is definitely off brand for us.
Matt Godbolt: Well, I don't know. There's,
Ben Rady: We're gonna statistically lose seven-tenths of our listener on this one.
Matt Godbolt: but the expected return of our, our listener reduces, but, you know, well, so, I mean, tell me about golf,
Ben Rady: Golf, man,
Matt Godbolt: And not code golf in this instance.
Ben Rady: No, not code golf or Frisbee golf, or, uh, there's gotta be other kinds of golf. No, I, so I've been playing golf for a long time. I've been playing golf since I was, uh, 10, 11, 12, somewhere in that range. And, uh, lately there's been a lot of changes to the game of golf and it's been, um, able to be quantified a lot more than it could in the past. And this has sort of exposed some sort of like, you know, well trodden, well known, you know, sort of old wisdom as being incorrect or misleading. And as a result, the game has changed pretty dramatically. And in fact, I think you could say that, um, in the last 20 years, golf has probably changed more than it has in the first 500 years. I mean, golf played since the 15th century. So, and to back this claim up, it's a pretty bold claim,
Matt Godbolt: There's a bold claim.
Ben Rady: Very, and to back this claim up, I would maybe point to the, one of the most recent major tournaments in golf PGA championship. Uh, the, the course had to be laid out in a way such that one of the tees was on the opposite side of a green of another hole. Like the golfers had to wait for the players on the green to clear before they could tee off
Matt Godbolt: Knocking a ball over their heads.
Ben Rady: They're hitting it over the, over the green, over their heads. And the reason for this is because, uh, the length of the course as it was originally laid out, which wasn't that long ago was just too short. It was too short for the modern game. And so they had to lengthen it and they didn't really have any space to lengthen it into. So they're like, well, we're just gonna put it on the other side of the green. And yes, that kind of sucks cuz it means that people are gonna have to wait, but this is my evidence for
Matt Godbolt: Crazy golf golf
Ben Rady: yeah. Yeah. It's like, it's like through
Matt Godbolt: The windmill golf now the other side
Ben Rady: Golf courses over the hill and under the thing and you gotta hit it through this pipe. Um, and, and, and sort of the changes that have occurred in golf and they're technological changes. But I think there are also some more sort of statistical changes as sort of the Moneyball effect that
Matt Godbolt: I was gonna say. It sounds very much like Moneyball, but you're saying this is over and above. Like, like what, what I might imagine is like better nutrition understanding of the physics of it, like in terms of muscularity and stuff like that. Something more strategic. What, I mean,
Ben Rady: I, I think it's two things. I think there's two things and, and they both have their own sort of nerdy aspects to it, but you know, today we're probably just gonna focus on one. One is the, just the technology, right, right. Like, uh, you know, balls, golf balls that fly farther, um, drivers that hit the ball farther, you know, distance has been sort of a main factor, but also, you know, technology around like, you know, spin and control and wedges and all these other things in the last 20 years last 25 years have changed really significantly, much more.
Matt Godbolt: Oh, interesting.
Ben Rady: Than I think that they have
Matt Godbolt: As a lay person, like a golf stick is a golf stick. Right. It's just a, it's a long tube of metal with a thing on the end of it. You hit the ball with, but you're saying there's a lot more sophistication than that.
Ben Rady: Yeah. Yeah. I mostly with golf balls, but also with, with, uh, clubs, specifically drivers. You know, like, you know, 50 years ago, uh, uh, like a, a driver with a metal head on it was a revolutionary thing. Right. Like they used to be made out wood. Good.
Matt Godbolt: There were woods. That's what I still think of them as, as wood. Right. Cause like my dad's old set would be made of wood, but yeah, I do remember the, the,
Ben Rady: Yeah. Yeah. And, and then, you know, they sort of invented like, okay, what have we made them out of, out of steel? And now they're made of out of carbon fiber composite. Right. Uh, Taylormade actually just came out with a new driver that is entirely carbon fiber composite. There's no titanium in it, which is what, um, so, so these kinds of developments have, have, especially for the pros, um, but also for amateur players really more for pros, uh, changed the game pretty significantly. Right. And then the other thing aside from sort of the technology, the equipment technology that changed is, uh, the stuff that I talked about, uh, uh, yesterday, which is being able to quantify things about, uh, the, the game about strategy, about swing golf swings, and the effect that they have on the ball, uh, in ways that, um, people were just kind of like assuming based on their observations. Um, I
Matt Godbolt: Right, right, right. Remember that sort of like cooking to completely take this off, off track, but I remember like a friend of mine, you know, this is pretty 10 years ago saying like, you know, so many things that we know know in quotes about cooking. Don't bear out if you actually try experimenting with it and try measuring it and try using like a heat lamp and whatever. I mean, you, you, you, you know about this stuff as well. But like yes. You know, because these things get passed down and without any way to check you go with the sort of essentially superstition over these things. And now you, you're saying we have ways of, of, of measuring and saying, are we actually doing what we think we're doing?
Ben Rady: Absolutely. Yeah. Yeah. So we have, uh, some of the more recent develops and again, developments. And I think, again, this is sort of like over the last 20 years or so you've got launch monitors, you've got devices that you can put down when you hit a golf club and using either high speed cameras or radar or both, it can measure very precisely, what direction the ball flies, how far it goes.
Matt Godbolt: you put down a thing on the one like, like near where your, your ball is and you like click a button or whatever, and then you sort of take your shot and it, and then, then you get some kind of telemetry about what the heck happened.
Ben Rady: Exactly. You don't even need to click a button. It just detects that there was a golf shot and it'll yeah. And it'll record that. Uh, and there, you know, there's, there's different mechanisms that they used to do this, but you can get very precise information about, um, what the face angle of the club was when it hit the ball. Was it pointing three degrees to the right? Or was it pointing three degrees to the left? Was it straight what the spin of the ball was? Is it came off the club, how fast it was moving the angle that it was moving at the angle that the club was moving down into the ball when it hit it, or was it,
Matt Godbolt: oh gosh,
Ben Rady: you know, maybe going up at a different angle, you know, how far behind or in front of the ball did it hit? And so
Matt Godbolt: That's a lot of information.
Ben Rady: Yeah. It's a ton, it's a ton of information and just,
Matt Godbolt: You know, take just noting out for a second there. Like, this is kind of pretty cool stuff if you're doing very high speed. Cause I mean, how are many I mean, this isn't a regular phone, uh, phone, regular camera cameras you might have on phone because like, I can't imagine in the small area that you are, that the club head and the ball are in that, that it spends more than a thousandth of a second in that kind of area, something of that order. Yes. And there's, that's like not very much time to record all that telemetry and to be able to look at it how amazing and to process it, and you say, you're doing spin, it's doing spin recognition. So presumably the dimples on the ball are enough for it to do like motion compensation
Ben Rady: and the markings. Yeah. Like the logo basically. Yes.
Matt Godbolt: Oh my God. So like there's, I mean, right. Just to get a bit of tech into this actual tech tech into this, like there's a lot of cool things going on in there. That's really, really clever. Yeah. But anyway, the result is you get a ton of information about your shot that allows you to make determinations, uh, about
Ben Rady: Whether
Matt Godbolt: What actually made the difference.
Ben Rady: And, and these devices now have come down in price, the technology's gotten good enough. They're very accurate. And they're not that expensive. You know, a really good launch monitor is, is kind of expensive cost about $20,000. Right.
Matt Godbolt: That's a lot of money.
Ben Rady: , that's, that's, that's the sort of the high end. Okay. But you can get ones for the, about, for the price of a, of a laptop computer. Okay. You get one, you know, for like $500 to 2000, $3,000, that are very good.
Matt Godbolt: If you take it very seriously, you know, as a hobby, that's not an totally unreasonable amount of money to to spend. Right.
Ben Rady: And the sort of democratization of this technology where it's, you know, and especially a lot of these things really took off with COVID cuz people were, you know, at home, not a lot to do wound up with a little bit of extra spending cash, cuz they're like, well, I can't go out anymore. I can't actually go out and play golf. Although they, they did eventually open that up. What do I do? Well go buy one of these launch monitors. And so the, the availability of these things and the sort of ubiquity of them has allowed people to talk about golf in a quantifiable way where they couldn't before. Right. You have instructors now that are, you know, used to say things like, oh, what you need to do is get your left arm a little bit more flat, right? Like that's, that's the way to improve your scores.
Ben Rady: And now you have instructors that say, no, what you need is to decrease your angle of attack with the club face from 7.2 degrees down to 4.2 degrees down because you're hitting down too much on the ball and you need to get it down from seven to four and you can have somebody that just sits there and like, you don't even need to tell them what to do with their arms or their body or their, whatever. You just say, try to hit it less down. And they're like, oh, I went from seven to 6.8. Good. You're improving. Do more of that. Well, I'm down to 5.2. Oh, that's great keep going.
Matt Godbolt: I was gonna say with all this technology, it sort of seems like it takes out the humanity of it somehow, but like not at all, because the skill level is still absolutely required to have that dexterity and fine motor control at that philosophy and strength that you're presumably putting into it as well, so. But it, it lets you have a very qu yeah. I, I, you know, I'm, I'm having a kind of flashback to my poor dad trying to teach me to play golf and standing behind me and telling me all the things that I'm doing wrong. And I'm sure he's right about almost all of them, but like, I don't know how I know I was definitely doing something wrong because I wasn't very good
Ben Rady: Right, right, right. And I think this has had a really positive effect on the game for lots of reasons. One is, is it creates a feedback cycle, you know, we talk about feedback on this podcast quite often. Yep. And it creates a feedback cycle that is, is, is much more, um, quantifiable obviously, but I think also much less prone to superstition. Yeah. Right. Like, like, oh, you gotta keep your head down or you gotta keep your left arm straight, you know, all these kinds of things like, okay, well what effect does that have on the ball?
Matt Godbolt: What does it really do
Ben Rady: What does that actually do
Matt Godbolt: if I pick my head up at the end of the shot. My head up at the end of the shot.
Ben Rady: Yeah. And it's sort of like, well, once you master it, it'll make your shots better. It's like, well, that's a long time away. And that seems like a really long investment to make, like, can I do something that will just make it better right now? And with these sort of like, you know, the, the sort of, um, impact dynamics and like understanding how ball flight works, which, which is another thing sidebar, uh, golfers were wrong about that for 500 years.
Matt Godbolt: What?
Ben Rady: like the way that ball flight actually works there's if you Google, uh, golf, new ball flight laws,
Matt Godbolt: Yes?
Ben Rady: You will figure out that only in the last 20 years have people actually figured out how golf balls really fly off a club. And that is due in, in large part because of these, these, this technology and these launch monitors.
Matt Godbolt: They're able to look at it and go, oh yeah, that's not, that's not true at all.
Ben Rady: Yes, yes, yes. So, so now we've, we've come into this world where you can say like, okay, I'm not gonna give you all this advice that might maybe one day be useful. I can look at the physics of the ball. I can measure what you're actually doing on this launch monitor. And I can tell you, yeah, the path of your club is to out by five degrees and that's too much, that's what causes your hook, right? So you need to narrow that down to two degrees and you will immediately see the, the flight of your ball change. Now, whether you can repeat that on the golf course or whether you can do other things is practice and you have to still all do those things.
Matt Godbolt: I mean, as, as a, as a lay person, like I could see that really gamifying it for myself to be able to, like, I know what I'm doing wrong and I can sort of fathom out what, what I might need to change, but when it's just randomly going off to the left and my dad saying, oh no, no, no, you need to open the club face or whatever. And I'm like, I'm, I think I'm doing that. And it's getting worse. I don't know if am I just doing it wrong or is there some supposition that we both have wrong? Is that not how it really works? That, that right. Really interesting.
Ben Rady: Right, right. Yeah. Yeah. Yeah.
Matt Godbolt: So that obviously makes a lot of sense, right? If you can understand the, the physics of the situation, then what you need to change to change the, both the, uh, the, the, the direction of the ball as it comes off the, uh, the club head and also the way it's spinning and interacting with the air and all that kind of stuff, but what else can you do with numbers?
Ben Rady: So, so the other thing that you can do, and this is another sort of, um, a, a more recent development, I think, uh, and the pithy phrase for this is a, a, a golf club is a shotgun, not a rifle. . Um, and what that means is that when you hit a golf ball, having an expectation that is gonna fly, you know, 150 yards, um, and land and roll out five yards or something like that is just a flawed way to think about, golf. What you should be thinking about is this is my dispersion area. I see I'm gonna hit a ball and it's gonna be somewhere in this area. And the essence of strategy really is just mapping that dispersion area for all your different shots. To the hole that's in front of you and trying to pick the one that has the best results,
Matt Godbolt: The most favorable outcomes, and the least unfavorable. So like a Montecarlo simulation of like, given that you are gonna be landing in this region with this sort of probability density, um, right. What's the right place to aim for, to get the best chance. Cause yeah, like you say, I mean, like, you know, my, my limit of playing golf is on the, Wii, so, you know, you know where it's gonna land because there's a dirty, great big line showing you where it's going to land and it bounces beautifully every time there's never any surprises. Right. But in, I, I have noticed that in real life that doesn't tend to happen, so.
Ben Rady: Doesn't really work that way.
Matt Godbolt: So yeah, you're saying actually, so there's a strategy here over and above. Just get it to this point. That's the nearest point you can get to without getting into the water and then go from the water to the, over the water, to the, the hole or whatever it is.
Ben Rady: Yeah. Yeah. And then sort of quantifying, like, what is the sort of expected value in that area?
Matt Godbolt: Yep.
Ben Rady: Is another place where both the sort of launch monitor technology and other technologies. So there's other cool things that they have. Um, and this is only possible cuz of GPS, which is only possible because of NASA, which is only possible because of, and you go all the way back all the time, see how all these wonderful things tie together.
Matt Godbolt: Einstein's theory, general theory of relativity.
Ben Rady: Exactly. So thanks Einstein for the ability for us to play golf in this way, where you have devices that you can attach to your golf clubs that will track all of your shots on the course.
Matt Godbolt: Neat.
Ben Rady: And that will give you some interesting information. It'll help you calculate these dispersion areas that we're talking about.
Matt Godbolt: Oh right. Empirically. So like, you know, yes, I was here with a seven iron and then I, it doesn't matter what I did. I landed in this region and I, I can play the same hole 20 times and go, where did I land from the the every time or whatever
Ben Rady: Exactly, exactly. Which you can also do in the launch monitor, you can compare those two results. Like you can hit, you know, 10, seven irons on a launch monitor and see what your dispersion area is. And then you can go down on golf course and you can play and you can take that data and, and, you know, correlate it together and be like, am, am I seeing on the course what I'm seeing on my launch monitor? No. Why not? Why not maybe wind or maybe I'm, you know, following a slightly different, uh, uh, you know, routine when I'm on the golf course, doing, you know, on a launch monitor, I'm just hitting the same balls over and over again. And I need to mix it up or whatever it might be. You could correlate those things and then taking all of this information and especially the, the shot location information.
Ben Rady: One of the more interesting things that the, the tour, the, the professional PGA tour did is in 2001, they built this system that uses laser range finding to measure to just a few inches where every golf professional on every tournament hits their ball. So there's this really rich data set.
Matt Godbolt: Wow.
Ben Rady: That, that is available. That you can get that, that shows for all of these different shots. And using that information, there was a guy named Mark Brodie that came up with this, uh, this technique called strokes gained where. There used to be, you know, lots of different ways to measure sort of the quality of a golf shot, right. People would say, oh, well, did you hit your, the green in regulation? Or did you hit the fairway? Did you hit the, you know, all these other things and these stats, like, they weren't really good. They didn't really tell you anything. And so what he wanted to do is, is to be able to compare from one shot to the next, from one player to the next, from one course to the next, how good was this shot? How can I quantify that? Right. Right.
Matt Godbolt: How do I rate a particular shot or
Ben Rady: Yes, yes. And he wanted to measure the unit of measure that he wanted to use was strokes. So he could make claims like that strategy that you chose was two tenths of a stroke worse than this other strategy. That you could have chosen
Matt Godbolt: I see fractional strokes here as well, like to be able to do a quantifiable analysis between things where. You know? Yeah. Okay.
Ben Rady: Right. So he wanted to be able to do that. So his method for doing this was basically, he came up with this system where he measured the average number of strokes that it took professionals. And amateurs, actually, he did this for amateurs too, but, but it was easier with professionals. Cause the data was there to say, how, how many strokes on average, does it take to hole out from a particular location on the course? So if you're, you know, 420 yards away on the tee. On average, that's like 4.1 strokes for a professional golfer.
Matt Godbolt: Right. Because it's a par four or whatever. And that's what the cold,
Ben Rady: Well, doesn't even matter what
Matt Godbolt: I, it doesn't matter. No, no, no, no. This is like an empirical determination. Yeah.
Ben Rady: Of it could be a par five. It could be a par four. It doesn't matter. We're measuring how many strokes does it take on average from golfers to hole out from this location
Matt Godbolt: From, from this particular. So there's kind of a map over, I'm sort of imagining a map of the golf course. Uh, yes. Where I can like see the contours of from here, where we'd expect to be four strokes from here, we'd expect to be three, two, and then once you get around the hole one or whatever, and that that's kind of your expected, if you could play like a professional
Ben Rady: Yes. An average professional,
Matt Godbolt: An average professional, right.
Ben Rady: From this location, the expected number of strokes would be 3.2, right. Or 1.6. Yep. Um, and so the way that he measures, the way that the system he came up with to do this was okay. We're gonna take the average from your starting location. Uh, we're gonna subtract one cause you're hitting a stroke.
Matt Godbolt: Right you're taking that shot, yep.
Ben Rady: If you take a stroke you'd expect to get one better. Right. And then we're gonna, and then we're gonna subtract the, the expected number of strokes at the ending location. So if you start out at a starting location and your average is 4.1 and you hit it, you hit a shot. So, okay. We're gonna subtract now and go down to 3.1
Matt Godbolt: Because like, given this system being perfect, then every time you hit a stroke, you should be one stroke, nearer to, the hole.
Ben Rady: You should be one stroke nearer to the hole. Right. Exactly. And then if you're ending location turned out to not be very good, like you didn't hit a very good shot ending location. Wasn't 3.1. It was actually like 3.3. Then you've actually lost two tens of a stroke on that.
Matt Godbolt: I see.
Ben Rady: Right. Whereas if you hit a better shot and your ending location was 2.8 than, you know, 3.1 minus 2.8, you actually gained three tens of a strokes you did better. Right. Does, and now you had this system that he could use to quantify and say like, okay, if you use, if you hit this shot, you gained two tens of a stroke. If you hit this shot, you lost four tenths of a stroke. I see. So clearly this is better.
Matt Godbolt: So that's where you, you, I empirically determined for any one position, like where you are, what, the way, what you should get and then hit the ball. Where did you end up? And then you can just say like, that was, I can say that it was a, a gained point too, of a, of a stroke there. Yes,
Ben Rady: Yes, yes. And this and this system takes into account the lie that you have, it takes into account how far you are from the hole. It takes into account. Whether or not you have a clear line to the flag. So if you have to like chip out, you know, something like
Matt Godbolt: That. Oh, I see if you're like behind a tree or yeah,
Ben Rady: Yeah, yeah. Yeah. If you're, you're stuck behind a tree,
Matt Godbolt: Again, all of my experience comes from Wii Sports really. So, I mean, we're not really talking
Ben Rady: Yeah. Yeah. Um, so you can imagine taking this information okay. And then combining it with the shot dispersion patterns.
Matt Godbolt: Oh!
Ben Rady: And now what you're basically doing is just trying to find an area with the lowest stroke or with the most strokes gained.
Matt Godbolt: Oh gosh. So you have a huge dataset of what actually happened, and you've got this, this map of where, what the scoring like expected score from any location is. Yeah. And then you can apply the two and kind of work out, see if there are patterns presumably in this data. Yeah.
Ben Rady: See if there are patterns and, and so, so to maybe, uh, make a video game out of this.
Matt Godbolt: Yes.
Ben Rady: Imagine you've got this,
Matt Godbolt: Now you've got me
Ben Rady: Little, you've got this little slider and you can just go through all your clubs. And as you change from you, seven iron eight hour, nine iron, you know, wedge, whatever. And as you do that, you can see the, your, your dispersion pattern for that club. Right. Changing and being overlaid on the hole. Right now, imagine furthermore, that the area inside your dispersion pattern, you take the, uh, strokes gained from that area and you, and you take the average of it and you just show it on the screen. Right. Ah, and as you sort of like, like let's say that you're, you're farther away from the hole. You're like, you're like 200 yards away from the hole. Right. And uh, you're like, okay, well I could, I could hit like my three wood that, that goes, you know, about 200 yards, but there's a creek that runs in front of the green. So as you go, as you scroll through and you go seven iron, you know, six iron, five iron, you know, five wood, three wood that stroked.
Matt Godbolt: Now you're in the danger zone of the creek.
Ben Rady: gained is going up and up and up. Right. And then all of a sudden you start intersecting with the Creek and then it starts going down again. Right. It's like, oh, cuz you might hit in the creek and that'll be a one stroke penalty. Right? And so like, and then as you move your aim left to right. You know, maybe you can hit it that far, but take the creek out of play. Right. And that's like the quantification of golf strategy. Right? It's like...
Matt Godbolt: Got it. You can run that Monte Carlo simulation and say like, what is my expected value for this club, given my abilities and my dispersion, um, and the actual lie that I'm currently in and the actual place that I'm gonna end up in, um, or like the likely areas and I can weight them, however, that's alright. So now, now you've definitely turned it into a video game where now, and well, in fact, what you've turned it into is what our day job is yeah. That's right. Which is sort of quantitative, like trying to find the, the minimum or the maximum of some kind of, of, of, uh, of, of complicated, very, very complicated feature set, which right. Is, is exactly what this is. Right. You know?
Ben Rady: Right, right, right. Wow. Yeah. And, and especially like more skilled golfers, it's not like they just have like their seven iron shot. Right. They have five or six different shots they can hit with the seven iron. Yeah. And each one of them has their own dispersion pattern. So, you know, you're talking about, you know, potentially hundreds of different patterns that you could potentially map onto a zhole. And so, you know, as a player or as a caddy, especially on tour, like you're standing there. Like, I don't think that these guys are like, you know, mapping these things out, quite on the course quite yet, but it wouldn't surprise me if that sort of thing starts to maybe happen a little bit. It's
Matt Godbolt: Pretty high, high stakesk stuff. So I mean, yeah. The, the drive to want to do this kind of stuff. So, so are there any like general things that come out of analyzing this data, you mentioned right at the beginning that like, there are some old folk wisdom things that have been shown to be wrong. So is, is that something in this that can, that we can, is there a conclusion we can draw from like this kind of data that, that would help even like someone is in it to myself?
Ben Rady: Absolutely. Absolutely. And you may remember some of these things from your youth being, being taught golf, there's, there's things about the swing that turn out not to be true. And there's things about strategy that turn out not to be true. Okay. Um, some of the thing, one of the things about the swing that turns out not to be true is I, I was taught as a, as a young lad, uh, cuz this is golf, um, that the way that you shape a golf shot. So the way that you control whether your ball is gonna, you know, curve to the right or curve to the left. Right, right. Because that's sometimes important in golf. If you gotta curve it around a tree or some other
Matt Godbolt: Around a dog leg or something. Yeah. Yeah.
Ben Rady: Something like that. Again,
Matt Godbolt: Wii sports is where I've seen this happen or, or not on purpose at the driving range when I'm doing it. Why, why is it going? Why is it going back?
Ben Rady: Why did it do that? Yeah, exactly. So the old school wisdom on how to do this, the thing that was taught by teachers and by professionals, you know, forever was that you pointed the face of the club at the place where you wanted the ball to wind up.
Matt Godbolt: Okay. Yes.
Ben Rady: And then you swung the club along a path that represented the way that you wanted the ball to start. Ah, yeah. So if you wanted the ball to curve toward a target, you would point the club at the target. And then if you wanted it to curve from the left to the right, you would swing the club to the left
Matt Godbolt: Effect, opening and closing the club face to, to point to where you wanna go. But then your swing direction is where it's is, is the launch direction effectively. Yes. Got it. I, I think that makes sense. Yep.
Ben Rady: Yes. Yes. Turns out that's completely wrong.
Matt Godbolt: Okay uh, you listening to this dad?
Ben Rady: You can look at...It's basically the opposite of that in a way. Um, the, the, the initial launch, you can see this on a, you know, high speed camera. You can, you can verify it with, with all of these new devices that we have available to us. Um, the initial path of the ball, 85% of that initial path is determined by the face angle. So the starting line is the face angle.
Matt Godbolt: It's actually the face angle. So like you hit it with yeah. Okay. Even though the club is kind of, yeah, I can't used hard to describe with that because I'm gesturing wildly at you, but right. But that's fascinating.
Ben Rady: Where, where the clubface is pointing at impact, uh, 85% of that initial direction is determined by that that angle Right? Where it curves is a function of the relationship between that angle and the path. And so the general rule is if you want the ball to curve, to a target, neither the face nor the club path should be pointing at that target. what you wanna try to do is, um, roughly, and unfortunately it's not exactly this okay. But roughly you want the club face to be pointing in between the target line and the path of the club.
Matt Godbolt: Okay.
Ben Rady: So, uh, so as a person who's trying to master this for the first time, I, I have these memories as a kid of like trying to, you know, set myself up as like, okay, I'm gonna point the club face at the target and I'm gonna swing along this path and I'm gonna hit it. And what I would see is that the ball would start at the target and then curve away from it off to the side. Yeah. And I'd be like, well, I guess maybe, maybe I had it wrong. What did I do wrong here? And it's like, no, that's exactly. You were doing exactly what you thought you were doing. It just doesn't work that way. Right. Um,
Matt Godbolt: How has that been so persistent for so long?
Ben Rady: I it's just super, it's like the cooking thing. Yeah. It's like, oh, you gotta sear the steak to seal in the juices
Matt Godbolt: Right, oh I was thinking exactly of searing when I was bringing this up. Isn't like, that's not a thing, it doesn't.
Ben Rady: It's like, no, that doesn't work like that at all. Right. It's just one of those things that it's like, oh, well, if you're an expert, this is what you say. And then that gets passed down and passed down and passed down. And then finally somebody was like, ah, guys, I don't, I got this video here at 20,000 frames, a second and you can kind of see it doesn't work like that. So I don't know what you were taught, but this doesn't, it doesn't go
Matt Godbolt: ...only if it works at all.
Ben Rady: Yeah. So, yeah. So, so that is, that is one thing, another thing, uh, and this is more on the strategy side, but it used to, you know, people had this pithy saying, uh, drive for show, put for dough. And what they meant by that was, is that putting was really important and driving was sort of seemed cool. And it's like, oh yeah, I hit the ball 300 yards, but it's really not all that important.
Matt Godbolt: That's absolutely what I, you know, as an extremely terrible golfer, like a friend of mine said, yeah, I, I, I learned quote, bad golf where, you know, if you're bad at golf, you can get by doing these things, just learn to, you know, putt reasonably well, everything else, you know, I basically play hockey with a seven iron down the, down the fairway till I get into the hole and then there's putting it. Right. And now I'm good, but I pretty could probably putt with the seven iron too. I just, that's the only club that I need.
Ben Rady: Just need a seven iron,
Matt Godbolt: Just a seven iron. It's fine. Right. Every, as you see, you can play many shots with a seven iron.
Ben Rady: Yeah. And I mean, you know, that's, that's honestly, that's not a bad way to play golf.
Matt Godbolt: Yeah. So, but it's not true. What, how is, how, how is that not true? And it is, how do you know it's true.
Ben Rady: It's very not true. How do I know it's not true? Is, is the real question we should be asking. So this is, gets back to Mark Brodie and, and his strokes gained approach. He wanted to try to figure out like, what makes good golfers good at every level. Right. Okay. At the PGA tour level, if you take the top 40 golfers, the best 40 golfers in the world, what makes them better than the rest of them that are on tour? Cause the rest of 'em on tour are so amazingly good.
Matt Godbolt: Right. Even
Ben Rady: But they're not as good as these people. Right. Yeah. Um, and so he looked at, he, he basically analyzed, he said, okay, well they, they perform better. I can use stroke gain to quantify how much better they perform. And I can break that down by category. Right. So how much does putting actually contribute to that top 40 players? Um, additional ability. It's actually only 15%.
Matt Godbolt: What, so that
Ben Rady: Is, so drive for show, put for dough. Doesn't really hold up.
Matt Godbolt: So sorry. 15% is, is go through that again for me cuz I'm being slow.
Ben Rady: So, so if you take, so let's take the top 40 golfers in the world. And let's compare them to the other professional golfers in the world. Okay. They gain more strokes in the strokes, gained methodology.
Matt Godbolt: Ok, you measure
Ben Rady: If you measure them by strokes gained. Right. So you like the top 40 golfers, let's just, I'm making these numbers up, but let's say that they gain like, you know, two and a half strokes on average versus all the other ones. Right. Right. Where does that two and a half strokes come from?
Matt Godbolt: I see. I see. And then you can say, where
Ben Rady: Did 15% of it comes from putting
Matt Godbolt: I okay. So of the overall improvement only 15 can be attributed to putting
Ben Rady: Exactly
Matt Godbolt: I get now. Exactly. Okay.
Ben Rady: And driving yep. Contributes to 28%. So almost twice as much.
Matt Godbolt: Okay.
Ben Rady: So it turns out driving as twice as important as putting
Matt Godbolt: Which again is like, so not the received wisdom.
Ben Rady: It's the opposite.
Matt Godbolt: Because, and especially, you know, like there's a non-linearity between accuracy and whacking it as hard as you possibly can. So, you know, maybe yeah. But so that maybe will work for professionals, but is that true generally?
Ben Rady: Yeah. So he did the same analysis. So, so he didn't have the, the shot link data, but he actually built an app to allow people to track their own shots. And there are other people, you know, I was talking before about those devices now that you can get that can, will track your shots and those devices have, have, uh, have reproduced his results. And show the same thing, which is that at every skill level. Yep. The thing that differentiates the higher skilled from the lesser skilled players is roughly this. So if we look at yeah. Um, on the PGA tour, so, so we talk about, you know, putting is 15% driving is 28% driving. Driving isn't even the most important thing. So the whole drive for show put for dough, it's like, well guys, you left out the most important thing, which is actually approach play hitting into greens. Right? Yeah. So getting from the fairway, hitting from the rough into greens.
Matt Godbolt: So not on the tee and not on the green, but like not on the middle bit.
Ben Rady: The middle bit right. Accounts for 40%.
Matt Godbolt: Oh my gosh.
Ben Rady: Of the difference. Right. So that is the, the dominating factor and it's, that's true at the professional level. It's also true at the amateur level. So for example, the difference between a golfer who usually shoots around 90. And a golfer that usually shoots around 80, 67% of their strokes gain of their advantage. Is from driving and approach play and only 33% is from putting and like chipping and sand shots.
Matt Godbolt: Same, same kind. So again, that sort of, yeah. Putting and, and the sort of special, special shots like is only a third of it.
Ben Rady: Out of sand...
Matt Godbolt: Two thirds is, is, is just,
Matt Godbolt: Yeah. Decent play in the, in the middle of the beginning. That's, that's amazing that you can get that amount of information and, or, I mean, I am genuinely surprised that it holds up in the amateur set. Cause again, based on personal experience, I can reliably chip the ball forward 50 yards with a seven iron. Right. If I don't try too hard and it goes roughly where I want it to go, but as soon as I try too hard, then that's when it's off into the undergrowth, then I'm searching around for it. Yeah. So obviously a base level of skill will help you with some, some amount. But
Ben Rady: Yeah. Well, one explanation for this, which makes a lot of sense to me, at least as a golfer is that I can hit an eight foot putt. You can hit an eight foot putt and you can have some expectation of making that eight foot pot. Right?
Matt Godbolt: Yeah. Okay.
Ben Rady: Uh, a professional can hit an eight foot putt and they're gonna make it more often than we do, but they can do that. That's a shot that they can hit. There's no way in the world that I'm hitting a seven iron 210 yards. I'm physically incapable of doing that. Right. I can't, I can hit a ball 210 yards, but it's not gonna have that like descent angle into the green
Matt Godbolt: That it's gonna make it.
Ben Rady: And the spin rate that'll make it hold and stick the green.
Matt Godbolt: It'll just run forever off forever.
Ben Rady: Yes. I have to basically hit a perfect shot to hit a shot onto a green from 210 yards. Uh, and I am just not physically capable of hitting this high arcing spinning shot onto a green from 210 yards that stays there. And so that's one explanation. And I think it's the one that Broadie likes and a few other people have said as to why this phenomena happens because, um, that advantage that professionals have that 40% advantage is being able to hit approach shots and specifically longer approach shots into greens. And that is just shots that, that amateurs just can't do. Like you can hit a chip for 50 yards. I can hit a chip for 50 yards Tiger Woods can hit a chip from 50 yards. But only tiger can hit a seven iron
Matt Godbolt: 200 yards yards and then land and have it stop abruptly.
Ben Rady: And then land and have it stop.
Matt Godbolt: And then that, yeah, that, again, down to the, the, um, the, the splash zone, the danger would call it like the,
Ben Rady: The, the dispersion
Matt Godbolt: Area, dispersion area, splash, splash stone. Yes. Um, of where the shot's gonna land. That's fascinating.
Ben Rady: Right. And, and also with driving, you know, Tiger can hit that 320 yard, or at least he could, his prime hit that 320 yard and professionals these days can hit balls 400 yards. I can't physically do that. You could gimme a thousand tries and I just wouldn't be able to do that.
Matt Godbolt: That's a very long way. Yeah, gosh. Yeah. So all this stuff comes around to, to, to sort of show us that, you know, you need data to be able to, you need data. I mean, you can convince yourself anything without data. Right. Right. Sometimes you can convince yourself anything when you do have data, you know, like, see, see, for example, benchmarking and micro benchmarks and other other things where you can kind of convince yourself, yeah, look, it's much faster this way only cuz the branch predictor has got everything right. Every time or whatever, whatever your folly is there. But, but in order to actually have some genuine understanding of what's going on and to be able to dispel myths and um, and superstitions
Ben Rady: Legends? Superstitions. Yes.
Matt Godbolt: Uh, you do need the data and, and now you can get it and there, and so is this open data, some of this stuff open data or is it all closed?
Ben Rady: So, you know, the, one of the complaints that I have about all this is that the ecosystem around some of this data is very closed. Like if you go and you buy these devices, and you record all your shots. Like, you know, I put that in there, that's my data. Yeah. But the only way that you can really get to it is like through their websites or through their apps. Right. And, and if the app disappears or the company goes out of business or whatever
Matt Godbolt: Your data is gone as well.
Ben Rady: Your data's gone. And it's like, and if I wanna load this into an Excel spreadsheet or like a,
Matt Godbolt: Because of course you do.
Ben Rady: You know, Python program of course, which I have done. Um, and analyze it myself. I can't do that. There's, there's one company that I, and I don't want to necessarily endorse anyone on the podcast, but there are companies out there that have more open data access that let you get your data. As a CSV file, which is exactly how I want it. Yeah. Right. Yeah. I just want a simple open, portable format, my data.
Matt Godbolt: Exactly. Right. And then you go and do tour own analysis
Ben Rady: and then I can go do my own thing. Yeah. Um, but most of them don't do that. They have these sort of closed ecosystems. Now it's good for them. Like the, one of the companies that, that, um, is very popular and unfortunately has a closed ecosystem's called Arccos. Um, and they have half a billion golf shots in their database. Right. Of amateur golfers that have hit real golf shots on real courses, measured with GPS. And I follow the head of data analytics, uh, at Arccos on Twitter, cuz he's got some amazing insights into golf. Yeah. But I wanna do that analysis myself.
Matt Godbolt: You wanna have access to that too.
Ben Rady: I want to reproduce his results right? Now. I understand why the company isn't exactly, uh, you know, forthcoming and sharing that.
Matt Godbolt: Well, yeah. I mean, especially aggregated data. I mean if just the privacy aspects alone, right. It's a part of it. Cause obviously you wanna have some idea about what quality level various golfers are and whatever. So you can partition the data.
Ben Rady: The data, but I can't even get my own data.
Matt Godbolt: That seems unforgivable
Ben Rady: To me. It is, it is now the launch monitor companies actually I think have been pretty good about this, right? Like they have more open formats and you can generally get access to your data. But all these companies that build like the club tracking, there's only one that I know of that lets you get your data off. And I think that's a damn shame.
Matt Godbolt: Well, a, a good friend of mine who I'm talking to right now has told me before, now that if you have a website, then you have an API. So is there any way that you could, uh, exfiltrate your own data?
Ben Rady: I have thought about that. I have thought about that.
Matt Godbolt: Of course you have.
Ben Rady: I, I was like, I was a little bit incensed by the idea of, okay, let me understand how this works. So I pay you $200 for these devices and then I pay you $30 a year for a subscription fee. And then I have to write the JavaScript. Uh bookmarklet that goes and extracts the data off your website. And it isn't even all the data that I would want. Like I want, I want lat longs. I want, you know, I want the, uh, you know, I want all of the data that I gave you. I just want you to give back to me. Right? Uh, and they, and some of that even doesn't show up on their website. So I, I, you know, I've been a little reluctant to sort of follow that path, but I have, I, I do have a system and they, um, the system that I have does allow you to export your data.
Ben Rady: And I, I actually just got it a couple weeks ago and I'm sort of like, you know,
Matt Godbolt: you're still playing with it.
Ben Rady: I'm like a kid in the candy store.
Matt Godbolt: That's great.
Ben Rady: Cause I have like one round of golf in there and I'm like picking it apart and going like, oh, I wonder if I could calculate this. calculate that. Yeah. So, so yeah, I mean, all this stuff is, is kind of amazing. And the fact that like, you know, it's really just like advances in technology that have made all of this possible. And I really do. I mean, it is a bold claim, but I really do think that golf has changed more in the last 25 years than it did in the first 500, you know? Yeah. Okay. The golf ball changed. We, you know, they used to play with what's called a feathery. Oh. Uh, which is basically a, a, a piece of leather with feathers stuffed into it.
Ben Rady: And that's your golf ball. And then they had the gutta-percha ball, which was like a rubberized ball. Uh, and then, you know, the balata ball, which is the ball that, uh, you know, was like a synthetic ball that, that golfers played with, you know, in like the fifties and sixties and seventies and eighties. And then it started to change. And I feel like that was the beginning of both the technological and sort of the quantification change in golf that has created the situation where it's like obsoleting golf courses, right. Golf courses that were made a hundred years ago
Matt Godbolt: Now are not fit for golf
Ben Rady: Are now are like, like we, what do we do? We gotta move the tees back. But there's nowhere to go. I see, go ahead. Um, so I feel like that's a pretty significant change.
Matt Godbolt: Well, I mean, I'd never thought that we would sit here on a programming podcast. doing essentially golf for hackers as we have done. But I mean, it's really fascinating. And uh, I, uh, I might even be tempted to pick up a, a golf stick myself.
Ben Rady: Well, if you ever wanna play, let me know.
Matt Godbolt: Okay. I will do.