Winning a PGA Tour tournament normally requires besting the field average by 12-15 strokes. However, Tour courses vary widely in difficulty between the US Open tracks which normally play several strokes over par and the easier resort style courses which can play several strokes under par. On the former, winning scores hover around par, while on the latter it often takes -25 under par to win the tournament. On difficult courses making mostly pars puts you in contention, while on easy courses a golfer needs to make a lot of birdies to even have a chance. What I was interested in is whether certain types of golfers perform better on difficult or easy courses. That is, are golfers who make more birdies than the field better set to tackle courses where you have to go low? And are golfers whose games are built on avoiding bogeys a better bet on hard courses where you have to grind for par? My research showed that there was a small affect in each direction, but one that doesn’t significantly impact most golfers’ results.
To set-up my study I collected the results for every golfer who played a qualifying number of rounds on the PGA Tour in 2013 and 2014 (~360 golfer seasons). I then adjusted their rates of birdie holes and bogey holes to account for the courses they played each season. In most cases the adjustments weren’t significant, but the better golfers tend to play harder courses and the worse golfers tend to play easier courses (there is positive relationship between the prestige of the tournament and the difficulty of the course). That yielded a relative birdie% and relative bogey% for each golfer. By subtracting bogey% from birdie%, you can find how dependent each golfer is on making birdies versus avoiding bogey for their scoring.
Last year, Rory McIlroy ranked 1st in birdie% and 4th in bogey%; he was more dependent on making birdies for his scoring. Jim Furyk ranked 39th in birdie% and 1st in bogey%; he was more dependent on avoiding bogeys for his scoring. I divided every golfer into one of six groups depending on how dependent they were on making birdies or avoiding bogeys. I’ll refer to those dependent on making birdies as Birdie Generators and those dependent on avoiding bogeys as Bogey Avoiders.
I then gathered the course specific scoring averages for each event, adjusted them by the quality of the field, and compared them to each courses’ par. For example, at the Sony Open in 2014 the field averaged 69.3, the field was 0.3 strokes worse than PGA Tour average, and the course par was 70. Adding all that together, an average field would have played that course in 1 strokes under par (70-(69.3-0.3)). For the 2014 Masters, the field averaged 73.95, the field was -0.3 strokes better than PGA Tour average, and the course par was 72. An average field would have played that course in 2.2 strokes over par (72-(73.95+0.3)). I then divided those courses into four groups based on their average difficulty; Easiest (>1 stroke under par), Easy (0-1 stroke under par), Hard (0-1 stroke over par), and Hardest (>1 stroke over par).
Read the chart with more negative values indicating better performance. The “Difference” column indicates the difference between performance on the easiest courses and hardest courses. Negative values indicate golfers in that group performed better on the easiest courses.
The results indicate that the most extreme Bogey Avoiders perform almost 0.2 strokes worse on the easiest courses relative to the hardest courses. The most extreme Birdie Generators don’t display the reverse, but with only eleven golfers, those results may reflect randomness because the next two less extreme groups of Birdie Generators definitely perform better on the easiest courses.
However, the results also indicate these values are not impacting tournament results for most golfers. Perhaps the most extreme Bogey Avoiders should be downgraded slightly on the easiest courses (like at the Humana this week), while it looks like the Birdie Generators definitely do play slightly better on easy courses and slightly worse on hard courses. However, even for the most extreme golfers, playing an unfavorable courses is only worth between 0.1 and 0.2 strokes different from their regular performance – enough to shift the odds of winning by around 1% for the best golfers and by much smaller fractions for lesser golfers. Going low is a skill, but it only makes a very small impact on real-world results.