What can stat geeks tell us about what it takes to win on the links?

The stadium scene.
June 18 2009 1:23 PM

Moneygolf

What can stat geeks tell us about what it takes to win on the links?

Illustration by Robert Neubecker. Click image to expand.

Tiger Woods is standing on the 18th green at Bay Hill, a golf resort in Orlando, Fla., owned by Arnold Palmer. He's wearing a form-fitting red Nike shirt and a black baseball cap. Widening his eyes, he gauges a 24-foot putt that he needs to sink to win the tournament. The announcer whispers—why do golf announcers whisper?—the following statistic: "It probably means nothing right now, but he is 0 for 21 this week on putts over 20 feet." Tiger strokes the putt. He sinks it! Hello, Ben Hogan! Just further evidence that Tiger is a great clutch putter, and clutch putting wins tournaments.

Or not. As golf researcher Mark Broadie has explained, professional golfers make only 15 percent of putts from more than 20 feet. So Tiger was actually below average in long putting at the Bay Hill tournament. While making the putt took great skill, it was some combination of other skills—most likely Tiger's extraordinary driving yardage, iron play, and good putting from other distances—that placed him in a position to win.

Scholars like Broadie have been looking at golf and trying to answer a simple question: Why do golfers win? They write papers with titles such as "Gender, Skill, and Earnings in Professional Golf" and "Modeling the Determinants of a Professional Golfer's Tournament Earnings: A Multiequation Approach." This week, the New York Times featured the work of two Wharton professors who analyzed 1.6 million putts and found that pros missed more when going for birdie than for par on putts of identical length. They chalked this up to "risk intolerance" (i.e., fear of making a bogey) and calculated that it cost the top 20 golfers significant prize money each year.

As that 1.6 million figure suggests, golf has rich data. Since 2002, the PGA Tour has deployed a system called ShotLink, in which a platoon of volunteers uses laser-measuring devices to record each and every shot. (The tour claims that its greenside laser is accurate to within 1 centimeter.) Before ShotLink, pro golfers had what you might call a King Lear problem: They but slenderly knew themselves. Given that one's score might vary by only a few strokes per round, it's hard for a golfer to detect where he is losing ground with his peers. With ShotLink data, they can now discern clear trends. Phil Mickelson, for example, realized his ability to get up and down from the sand was subpar. In two years, he improved dramatically, moving from a ranking of 180 to 3 in sand saves.

So golf stats certainly help the pros fine-tune their game—but what about the fan at home who wants to put a little money down? Is there a killer stat to look for? Probably not.

In 2005, economics professor Stephen Shmanske published "Odds-setting Efficiency in Gambling Markets: Evidence From the PGA Tour." His determination: "Unfortunately, readers of this paper will not be getting rich anytime soon by handicapping professional golf." The odds-setting strategies that casinos have been using are sound. When Tiger was in the field, he was the favorite. When Tiger wasn't playing, the field was the favorite. Shmanske found that the odds captured the four skills that consistently win tournaments: driving accuracy, driving distance, greens-in-regulation, and putts per green. (Hitting a green-in-regulation means that you reached the green of a par 3 in one stroke, a par 4 in two strokes, and so on. It's a measure of accurate iron play.) He concludes by offering a slim hope that "other variables" such as the "hot-hand tendency" (golfers on a win streak) or "expected weather patterns" (some guys play better in the wind) may offer odds-beating predictive power.

What Shmanske's paper does offer is predictive power about golf studies in general: Tiger Woods warps everything, and, despite the explosion of golf data, a mere four skill stats have the greatest correlation with professional success.

My favorite example of the Woods effect came in the paper "Match Play: Using Statistical Methods To Categorize PGA Tour Players' Careers," which divided players into groupings of Elite, Distinguished, Established, Journeymen, and Grinders. (It's hard out there for a Grinder. The authors conclude: "We found that players on average spend significantly less time improving on their rank and more time staying the same or getting worse.") Woods' career stats are so good that he's statistically very close to forming a group of one. (Godlike?) He is literally a league of his own.

Though the four skills that correlate with winning have been established in the literature, there is debate about how influential each of them is. Specifically, has increased driving distance altered the traditional formula for victory? The short game—any shot from within 125 yards—has traditionally been more prized as a skill set than crushing the ball off the tee. "Drive for show, putt for dough," is the timeworn adage (usually said after your partner hits a great drive). But what if the ability to drive the ball 300-plus yards gives a player a significant advantage? An article in Chance, themagazine of the American Statistical Association, finds that greens-in-regulation and putts-per-round are still most crucial. But there is some evidence that, as players have gotten longer off the tee, driving accuracy is now less important.

The real-world application of this insight can be seen in the "bomb and gouge" strategy on par 5s. Whereas players were once criticized for being reckless by stretching to reach a par 5 in two shots, it's now conventional tour wisdom to crush your drive as far as you can. No worries if it lands in the rough—it's better strategy to dig it out and try for the green in two.

Some gurus like Hank Haney, who coaches Tiger, hold that power is the most important factor for determining the potential of a golfer. Haney represents a school of golf thinking that's annoyed by the importance of putting. Ben Hogan is on record as complaining that "there is no similarity between golf and putting. They are two different games, one played in the air, the other on the ground." Some former pros have suggested that putts be worth half a stroke, or that the hole be made twice as big.

This last idea caught the fancy of Mark Broadie, the golf researcher. Who would benefit from a larger golf hole? Good putters or bad putters? Your gut would say good putters. They're already burning the edges of the cup, so more of their putts would fall in. But when Broadie ran a simulation, he discovered that the bad putters would be doing more high-fives around the green. It turns out that the good putters don't have many 3-putts. They are 1-putting or 2-putting most greens and simply don't have a lot of room to improve. The bad putters would see some of their 3-putts become 2-putts and pick up strokes.

Broadie also pokes a hole in another piece of conventional golf wisdom. Many good golfers have a distance from the green where they feel most comfortable hitting approach shots—perhaps they like to hit a 9-iron from 120 yards. So, on a par 5, if they can't reach the green in two, they will often hit their second shot into that comfort zone, the strategy being that it's better to groove a 9-iron than to sweat over a 40-yard wedge. Broadie has found that the "comfort zone" feeling doesn't hold up. Everybody gets better—they hit it closer—when they are closer to the green.

Though Broadie questions some elements of professional golf strategy, he hastens to point out that the pros are significantly better at all aspects of the game than amateurs. Indeed, stats get most useful when you start to look at mortal golfers—our mistakes make more of a dent in the data. Broadie has created a software application called Golfmetrics that helps capture the rounds of weekend hackers and scratch golfers alike. At the 2008 World Scientific Congress of Golf, Broadie presented his finding that consistency is underrated in golf. High handicappers are harmed most by the few absurdly bad shots in each round, like, say the wedge you skull 40 feet sideways.

In support of Haney, Broadie says that the long game is what separates the pros from the rest of us. The ability to hit it both longer and straighter is huge. Here is Broadie's vivid example: "If a low-handicap golfer had Tiger Woods do all of the putting, the gain would be about 2.2 shots per round, but having Tiger Woods hit all shots over 100 yards would lower the score by about 9.3 shots per round." But once you start comparing pros to pros, putting becomes important again. Indeed, the margins of skill difference between great pros and slightly greater pros are so slim that you must put down your calculator and start discussing the unquantifiable mental aspects of the game. Which is to say that you have left the realm of Moneygolf far behind.

Oh, what's that, I've forgotten something? Yes, Tiger Woods will win the U.S. Open this week. Just don't expect him to make many 20 footers.

Slate V: How To Make Golf Exciting

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