By the Numbers

Peter Sanders David Dusek/Golfweek

By the Numbers

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By the Numbers

BOSTON — The recently concluded MIT Sloan Sports Analytics brought together some of the most cutting-edge researchers and brightest minds in the world of sports statistics. Titles of panel discussions and lectures included, “Leveraging Machine Learning and Pitch F/X Data to Illuminate the Impact of Pitch Framing,” and “Real-time Interactive Play Sketching with Synthesized NBA Defenses.”Former Microsoft CEO and current Los Angeles Clippers owner Steve Ballmer spoke, as did former NBA stars Shane Battier and Steve Nash, former baseball star Alex Rodriguez, former president and general manager of the Philadelphia 76ers Sam Hinkie and former President of the United States Barack Obama.

Golf was there to in the form of Peter Sanders, the founder of ShotByShot.com and the stats guru to numerous PGA Tour players, including two-time major winner Zach Johnson. His lecture, entitled “From Stats to Strokes Gained: The Evolution of Golf Analytics” was given in front of about 150 people in a side room on the first morning of the two-day conference. It focused how why some of the most popular stats in the history of golf are, basically, worthless and thanks to the PGA Tour’s ShotLink system, which began in 2003, strokes gained statistics have given us a better understanding of the game.

Among the insights that Sanders shared were:

  • Every week, the player who wins makes an inordinate number of putts from 11 to 20 feet.
  • According to Sanders, about 33 percent of all first putts are 20 feet and longer in length, and when faced with a putt from over 20 feet, the best putters in the world leave themselves within seven percent of the first putt’s length, or 3 feet, more often than other players. Since players on the PGA Tour make putts from inside 3 feet about 99 percent of the time, the best putters almost never 3-putt.
  • Everyone on the PGA Tour plays under par when they play from the fairway. “If you look at the scores after a tour player hits the fairway, the top-five players hit the fairway and even the guys who get cut, they all average under par on those holes,” Sanders said, citing the data in the table below. “From the rough, they don’t, except for the players in the top five. The average difference between playing from the fairway and hitting the rough is about a quarter of a shot.”
Players Fairway Score Rough Score Difference
Tour -0.16 0.12 0.28
Top 5 -0.25 -0.01 0.25
Cut -0.05 0.23 0.28

 

  • According to Sanders, the most-frequent approach shot distance range is 150-175 yards, and in order for the average tour player to hit the green from the rough as frequently as he will from the fairway that range, he will have to be 50 to 75 yards closer to the hole. “The message I give to the players I work with is that if you have to lay back 25, 30 or 35 yards to avoid the rough or trouble, you are not giving up any shots,” Sanders said. “You are gaining shots.”
  • However, when golfers do not have water or a hazard guarding a green on a par 5, they are almost always better off going for the green instead of laying up. The reason, according to Sanders, is clearly visible in the chart below.

 

75-100 yards Percent Who Hit the Green Average Distance to the Hole
Tour 85 percent 15 feet
<50 yards Percent Who Hit the Green Average Distance to the Hole
Tour 93 percent 7.1 feet

Players who go for the green in two shots on a par 5 and hit their third shot from within 50 yards of the hole hit the green with their third more often and get the ball closer to the hole with that shot too.

“They cut their error percentage in half and they cut their average putting distance in half,” Sanders said. “So my message is that if there is no obvious downside, go for the green every time.”

Surprisingly, Sanders said that most coaches who work with PGA Tour players see the hundreds of stats created in the ShotLink system as a giant, confusing mess. It’s a system that is filled with numbers and definitions that they do not understand, and they don’t know which stats to pay attention to and which they probably should ignore.

Even more surprising, four minutes into Sanders talk, he said, “If you know what strokes gained is, then you are in the vast minority. I start our all my initial meetings with tour players and their coaches by giving examples and it invariably leads to very spirited conversations about what these numbers really mean and how they relate to traditional statistics.”

To ensure that you are in the wise minority, it is important to understand that stokes gained statistics are all based on the average number of shots it will take to get the ball in the hole from a given distance. Those average numbers have been created by studying tens of thousands of shots measured using ShotLink over the years. Here is a simple example of how strokes gained stats work:

Imagine that a PGA Tour player is playing a 460-yard par 4. Based on historical data, we know that the average number of strokes needed to get the ball in the hole from that distance is about 4.17. After the player hits a tee shot 300 yards, his ball is in the fairway 160 yards from the hole. The data says that the average number of strokes needed to get the ball in the hole from there is 2.98. If you take 4.17 and subtract 2.98 (which equals 1.19), and subtract one to account for the shot that was taken, we know the value of that 300-yard drive was 0.19 strokes.

If the player hits his next shot on the green, but 60 feet from the flag, the data says the average number of strokes needed to get the ball in the hole is now 2.21. So, 2.98 minus 2.21, minus one for the shot the player just took means the approach shot was -0.23. However, had that second shot stopped 10 feet from the hole instead, where the average number of shots needed to get the ball in the hole is 1.61, the approach shot would have been worth 0.37 (2.98-1.61-1).

If the player makes the 10-foot putt, the value of the putt would be 1.61 minus one, or 0.61 shots. If you add up the strokes gained value of the drive, the approach shot to 10 feet and the putt, you will see that this player gained 1.17 shots.

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