Continued (page 2 of 4)
The location of trees is not part of the ShotLink course mapping, nor is a terrible lie in the rough differentiated from a good one. Mapping trees is not the answer, because there are too many variables in the types of shots players can hit, including going over the trees. In any case, it would be hard to differentiate between a great recovery shot into a greenside bunker and a mediocre shot into the same bunker from a more favorable position or lie.
Broadie has tackled this problem by determining zones on tour courses from which a recovery shot is required based on historical data, and in those cases penalizing the shot that put the player in that position. Sanders mines the ShotLink data for the PGA Tour pros he now works with and is able to break down missed fairways into the categories of good miss, poor miss and no shot, developing an algorithm to determine the worst outcome.
But the tour has additional issues. While Broadie is typically looking at the long term, where inconsistencies even out, using recovery zones to determine the worth of shots could lead to misleading results for a given round. "We're being very obsessive about trying to accommodate all kinds of situations," Evans says. In an effort to make any new strokes- gained stats work in real time, the tour is trying to develop a computation that doesn't use historical data. It is hoping to avoid using subjective judgments by the walking volunteer scorers as to the difficulty of recovery shots, but in the end that might be part of the equation. (Currently the scorers make a note if a lie in the rough or bunker is "buried," but that information is generally not used.)
So, the tour is taking a gradual approach. Sometime during 2014, it will unveil the new statistic of strokes gained/tee to green. It essentially will subtract strokes gained/putting from a player's stroke differential versus the field in a given round. For example, if a player shoots 68, the field averages 71.0 and his strokes gained/putting is 1.0, his strokes gained/tee to green is 2.0 to account for the total of three strokes gained on the field. That's simple enough, but even this rollout has been delayed by some additional related computations.
Meanwhile, Broadie is constantly refining his analytics. For example, one difficulty with analyzing short-game and approach-shot data strictly by distance from the hole is the short-side situation. All things being equal, shorter shots would be easier, but that's often not the case on the PGA Tour where missing on the short side of a hole location near the edge of the green often creates a difficult shot.
"I've spent quite a long time thinking about that problem," says Broadie, who is currently working with a grad student on a research project in that area. "We are taking a look at how we can adjust strokes gained for other factors that can be measured in the data, like whether a player is short-sided, the elevation change between the ball and the hole, the slope of the green, the angle relative to the fall line and the kind of lie if that is available."
Broadie has also spent quite a long time analyzing the data to determine the aspects of the game that contribute the most to low scoring and to winning tournaments. He conveys those results, along with suggestions for strategy based on the data, in an upcoming book, Every Shot Counts, to be published in March by Gotham Books.
Many of the results show that conventional wisdom is not to be trusted. For example, breaking down the ShotLink numbers for the top 40 players from 2004 to 2012, Broadie shows that approach shots accounted for 40 percent of their scoring advantage, driving accounted for 28 percent, the short game (shots off the green and inside 100 yards) for 17 percent and putting for 15 percent.
"The importance of the long game versus the short game is surprising to many people, but looking at the data it is striking how true it is throughout the whole range, from top pros to lesser pros to amateurs," says Broadie. "It becomes clear if you think about some examples. If I were playing a par 5 of 550 yards and I could have Tiger Woods hit the shots outside 100 yards or inside 100 yards, I think it's pretty clear I would choose outside 100."
Proponents of the importance of putting might be encouraged by the fact that wielding a hot putter is somewhat more of a factor in winning, as putting contributes 35 percent to victories as opposed to 15 percent to being a top player overall. However, that still leaves tee-to-green play the greatest contributor to taking home the top prize. In the 2013 season, the week's leader in strokes gained/tee to green won eight times and finished second 11 times in the 30 tournaments where all four rounds were covered by ShotLink, finishing out of the top 10 only once. The week's leader in strokes gained/putting won only twice with just four runner-up finishes, missing the top 10 fully a third of the time.
Players can sometimes win with mediocre or even substandard putting, but much more rarely with mediocre play from tee to green -- in 2012 and 2013 combined, 10 players won while ranking worse than 25th in strokes gained/putting but only two did so ranking worse than 25th from tee to green.
Another conclusion Broadie draws from the data is that driving distance is a greater factor than driving accuracy to scoring. That's the reason long hitters like Bubba Watson populate the top of the strokes gained/driving standings, though accuracy is important enough to hurt a very wild driver like distance-leader Luke List. A 20-yard advantage in driving distance leads to a fractional advantage on every stroke, and over the long run that adds up. Strokes gained/driving also reflects the advantage gained by being able to go for the green on reachable holes more often, an edge that isn't reflected in traditional stats like greens in regulation.
Going back to the point at the top of this story, Watson trumps Graham DeLaet in strokes gained/driving simply because averaging two rankings, as in total driving, is a flawed mathematical way of determining who is best at a combination of two factors (DeLaet ranked 17th in strokes gained off the tee). For approach shots, strokes- gained is superior to even a seemingly advanced stat like proximity to the hole because it better reflects the likelihood of making birdie or bogey after the approach. And all of the strokes- gained stats are adjusted to the field average at each event, taking away the disadvantage in the regular stats of playing a tougher schedule.
With the advances in statistical analysis, it should come as no surprise that some players have started to use ShotLink numbers to help their game. One of the early adopters was Luke Donald, along with his instructor Pat Goss. The start of Donald's pro career nearly coincided with the start of ShotLink, a fortunate coincidence for Goss, Donald's coach both at Northwestern and for most of his pro career. (Donald has recently switched to another swing coach but still relies on Goss for the short game and statistical analysis.)
"The old stats didn't have a lot of value. They never told the story correctly," says Goss, who has an economics degree. "For a guy with a background in stats, it didn't feel like there was enough info to make it worth the time. Even with ShotLink, we are just beginning to brush the surface."