Book excerpt: "Every Shot Counts"
June 10, 2014
By Mark Broadie, PGATOUR.COM
- June 10, 2014
- Approach shots were the key to Justin Rose's stellar year in 2013. (David Cannon/Getty Images)
Adapted excerpt from Mark Broadie's book "Every Shot Counts" for PGATOUR.COM
One year ago Justin Rose won his first major, the U.S. Open, at Merion Country Club in Ardmore Pennsylvania. We know he won by shooting the lowest score, but that doesn't tell us how he won.
Measuring golf performance requires comparing skills that had been thought of as apples and oranges. Bombing a drive down the middle of the fairway requires strength and timing. Hitting a chip shot requires precise contact for the ball to travel the desired distance. Sinking a downhill double-breaking 20-foot putt requires green reading skill and putting touch. One appeal of golf is the many different skills required, yet this also makes it challenging to figure out a method for measuring the relative importance of different parts of the game.
Traditional golf stats, fairways, greens and putts, just aren't up to the job. Prior to the age of powerful computers and laser technology, these traditional stats were the best that could be done because they only involved counting. Add one to the fairway count if a golfer hit another fairway with his drive. Add one to the putt count for another stroke on the green.
But counting is misleading. A count of fairways doesn't distinguish between a big miss (out of bounds) and a small miss (in the rough). A count of putts doesn't distinguish between a two-putt from 60 feet (a good performance) and a two-putt from two feet (a horrible performance). Better measures of golf performance require better data.
Enter the PGA TOUR and their shot-level data collection system called ShotLink. Beginning in 2003, the PGA TOUR has recorded detailed information on every shot taken at its tournaments, using laser technology and about 350 volunteers at each event. The ShotLink database, powered by PGA TOUR technology partner CDW, now contains detailed information on more than 11 million shots. Unlike systems based on GPS, the laser-based ShotLink system is very accurate, with locations on the green measured to within two-inch accuracy and off-green locations measured to within one-yard accuracy. This vast store of accurate information is just what I needed to analyze and assess the performance of the best golfers in the world.
The lynchpin of the analysis in Every Shot Counts is the strokes gained concept, which allowed me to work with the new mountain of shot-level data to compare parts of the game that had never been measured with the same stick. Here's a brief explanation of strokes gained: If a stroke starts on a tee where, according to historical data, the average score is four, and if it finishes at a position in the fairway where the average strokes to hole out is 2.8, then the tee shot has moved the ball 1.2 strokes closer to the hole with just one stroke. The single tee shot has gained 0.2 strokes compared to an average tee shot, so it has a "strokes gained" of 0.2.
Strokes gained recognizes that sinking a 20-foot putt represents a better performance than sinking a three-foot putt, even though they both count as a single stroke on the scorecard. Strokes gained assigns a number to this intuition. Though strokes gained has roots in some fancy mathematics developed at the dawn of the computer age, there is an elegant simplicity to a stat that, at its core, merely involves subtracting two numbers.
I can’t do a detailed analysis of the play at the U.S. Open because the United States Golf Association does not record the same type of shot-level data. I wish they would (anyone listening at the USGA?). But I can use the strokes gained method to analyze the PGA TOUR’s ShotLink data and identify the keys to Justin Rose's stellar play in 2013. It’s very important to identify the type of player who wins a major rather than just analyze what happened in a single event.
Throughout the entire 2013 season, Rose was ranked 3 in total strokes gained, gaining 2.18 strokes per round on his competitors. Approach shots, that is, all shots that start outside of 100 yards from the hole excluding tee shots on par-4 and par-5 holes, contributed a gain of 1.09 strokes, or 50% of the total.
Strokes gained per round Justin Rose (2013)
Total Drive Approach Short Putt Rank 3 10 3 6 127 Strokes gained 2.18 0.62 1.09 0.57 -0.10 Fraction of total 100% 28% 50% 26% -5%
Strength in approach shots alone is not enough to win golf tournaments. Rose combines his superior approach play with a strong one-two punch in driving and the short game. Putting is a weakness, but he has putted very well in many tournaments and extremely well in many rounds. In the first round of the 2013 Arnold Palmer Invitational presented by MasterCard, Rose gained a remarkable six strokes on the field with his putting.
Rose's primary strength in approach shots isn't unusual among the world's best golfers. A strokes gained analysis of millions of shots in the PGA TOUR's ShotLink database shows that approach shots account for about 40% of the scoring advantage of the top forty pros on the tour. Within the broad approach shot category, it's the longer approaches (shots that start between 150 and 200 or so yards from the hole) that contribute the most to the scoring advantage.
The new insights provided by a strokes gained analysis of the ShotLink data are a surprise to many, but to Sean Foley, coach to Justin Rose and Tiger Woods, it confirmed what he already knew. Foley wrote in the foreword to Every Shot Counts, "We'd always been taught that the important thing is hitting it in the fairway and hitting it on the green, but my intuition had told me long iron shots were important. Everyone's always telling me your guys should be practicing a lot more wedges, but I just don't see them hitting many 80-yard wedge shots in a round. I've always wanted my guys practicing a lot of 190- to 230-yard shots. And here were the strokes gained numbers to support that."
Foley continued, "Traditional golf stats today are like a plane that's circling the airport until it runs out of gas. It's going to either land or crash. People are in a comfort zone, and they're not willing to go through the pain or doubt that goes with developing a new way of thinking. But at some point, Mark's approach will become how people determine golf performance. They're just going to have to accept it, because it makes too much sense."