Little did we know, Chevy Chase might have been onto something here.
One issue with modeling golf skill, as opposed to other sports, is that we rarely have anything to go off of other than prior performance. In Basketball, we can look at a players height and athletic ability, and synthesize those numbers with his college stats in order to predict how he might do as a pro. But in golf, none of that seems to matter, at least on the surface. There are players like Tony Finau, a 6’4″ former basketball player with a ton of athletic ability. And there are players like Brian Harman, a 5’7″ 150 pounder who could not possibly be successful in any other sport. And then there are even guys like John Daly, who was tall, overweight, and out of shape, but still experienced quite a bit of success as a golfer. It’s the beauty of golf, you can be any shape or size and be great. But is there a specific height or weight that’s more conducive to success?
One thing that peaked my interest in this is the aforementioned Brian Harman. Brian Harman is the bane of my golf betting existence. Halfway through the 2017 PGA season, I decided that putting from year to year was the most luck-based aspect of golf (true), and because of this, bet on every bad putter hoping they would regress to the mean, while fading every “hot” putter (this was not my smartest moment). Brian Harman was one of these supposedly hot putting players. Jason Kokrak was a player I viewed as “running bad.” I bet against Harman and on Kokrak for several tournaments during the latter half of 2017. But, to my frustration, Kokrak kept putting pretty poorly for the 2017 season, and Harman stayed hot, completing his year with 7 top 10s and a win. In my eyes, my bets were unlucky.
But Kokrak and Harman have one massive difference that I may have overlooked. Harman, as I mentioned earlier, is one small dude. He’s 5’7″ and listed at 155 pounds, and possibly smaller given most people exaggerate their height on the high side and that weight number probably doesn’t come from Harman stepping on a scale. Kokrak, on the other hand, is huge at 6’4″ 225 pounds. I had a hunch. I decided to take a look and see if height and weight had any correlation to putting skill. Thanks to the new Strokes Gained stats on pgatour.com, we can actually see which golfers have performed best putting over the last few years. So I found some height and weight data for professional golfers, and combined it with strokes gained data over the last 4 years. The first thing I wanted to see is if strokes gained putting correlated with height or weight. Here’s what I saw:
For clarity, avg_2017, avg_2016, etc. is the strokes gained putting average per round for a player in that particular year. Total_sg_putt is the total strokes gained putting a player had cumulatively over the last 4 years of his career (I’m only using data for players who have played on the PGA tour 4 years in a row). Height_inches and weight are height in inches and weight in pounds.
And here’s a correlation matrix of my results:
As you can see, height and weight both have a negative correlation to total SG putting. Height was a bit more consistent of a factor year over year, but had a lesser overall negative correlation compared to weight. Weight was the more inconsistent of the signals, while it seemed to matter quite a bit in 2014 and 2017, it didn’t matter much at all in 2016 or 2015. Both stats aren’t perfect, but the negative correlations were enough to make me think I was onto something.
Finding relevant stats like this, unrelated to past performance in anyway, can be quite helpful for modeling performance. It was an exciting discovery. I already had a linear model for yearly strokes gained putting, which used the previous years SG putting average and the combined sg putting total from the two years before that. The R-squared of this model was ~.25.
I decided to turn height and weight into z-scores (essentially, changing it from inches and pounds to standard deviations above or below the mean height and weight) and combined them into a stat I called height_weight, and added it to my model. My thought was that since height is correlated to weight (a 6’4″ person is almost always going to weigh more than a 5’9″ person), that combining them would give me a gauge of overall size and might be a better metric. Adding it to my linear model, I ended up getting an rsquared of .28! A significant (although obviously not massive) improvement.
I have a few theories of why this might be the case. Weight is likely related to physical fitness, and being fit overall likely adds to to the fine motor coordination needs to have a steady putting stroke. As for height? It’s possible that having shorter arms can mean a shorter, steadier stroke. Or it’s possible that being simply having your head closer to the ball helps aim and hand-eye coordination more. Regardless, it seems to matter for one reason or another. Out of the top 5 putters in the strokes gained putting metric in 2017, all of them we’re under 6′ tall, 3 out of 5 we’re under 5’9″, and 4 out of 5 weighed under 170 pounds. It’s possible height or weight can put a ceiling on putting skill.
Over the past few years, there have been many new up-and-coming young faces on tour who have experienced quite a bit of success. Jon Rahm and Rickie Fowler are two of these players, and they were paired up in the 2nd to last pairing during the final round of the Masters this year. Both looked as though they might make a run at 1st place, with Rahm coming up short after hitting it in the water on the 15th hole and Fowler finishing in 2nd place, just one stroke behind eventual winner Patrick Reed. Both of these players represent the future of golf. But one distinct difference between them was as clear as day on TV. Fowler is short and small (5’9″ and 150 pounds, to be exact), while Rahm looks like he could be a linebacker (6’2″ 220). Sadly for Rahm, if he chose another sport, that linebacker build would be to his advantage. But in golf, it turns out Fowler has the superior height and weight. When it comes to a debate for the future of golf, whether Jon Rahm or Rickie Fowler will be the next player to win his first major, or whether Brian Harman or Jason Kokrak will have a better career, I’ll be betting on the small guys.