History Of Strokes Gained


In the last few years, the golf world has been introduced to a powerful and elegant new statistical methodology called “strokes gained”. Sports like basketball, baseball, and football have seen dramatic change in recent years due to advanced metrics and analytics. Golf is now poised to join these sports with dynamic and versatile analytics that promise to revolutionize the sport.

Deficiency of Traditional Stats

Many people who understand the game of golf have long known, or at least suspected, that standard golf statistics can be very misleading, particularly when it comes to measuring the skills of a golfer in a given category. For example, the statistic called “Total Putts” is often used to measure the putting skill of a golfer. However, “total putts” is a very poor reflection of putting skill because it is strongly tied to a non-putting skill: the proximity to the hole of an approach shot is a major factor in how many putts a golfer would be expected to take to finish a hole. Consequently, a golfer who hit approach shots to an average of eight feet from the hole for a round might take 30 putts in a round. Another golfer who hit approach shots to an average of 25 feet from the hole for a round could also take 30 putts for a round. The “total putts” statistic would indicate that the golfers had equivalent putting skill for the round. It is obvious, however, that the second golfer had a dramatically better round of putting.

Similar examples can be given for other standard statistics. The “driving accuracy” statistic is a poor measure of skill off the tee: a 300 yard drive in the middle of the fairway is greatly superior to a 200 yard drive in the center of the fairway. “Driving Distance” is no better: 310 yard drives in deep rough, or into other trouble, are clearly inferior to 260 yard drives in the fairway. Combining those two statistics into a new statistic called “Total Driving” does not solve the problem, and in many ways makes it worse.

Even long-standing statistics like “Greens in Regulation” are deeply flawed. Designed to reflect skill from tee to green, the statistic does not take into account the proximity-to-hole of approach shots, giving equal value to approaches two feet or 80 feet from the hole.

Development of the Strokes Gained Stat

A major advance in golf statistics began around 2003, when the PGA Tour began to employ a unique data collection system called ShotLink™. ShotLink™ comprises data for millions of shots taken by professional golfers during tournament play since 2003. The ShotLink™ system is operated by a small staff of employees and a large volunteer workforce. It normally takes approximately 250 volunteers per event to collect data for a golf tournament, using laser technology to measure distances and physical observation to determine lie type, along with significant additional technology to collect and store the data.

Around the same time the PGA Tour was beginning to collect detailed data on the PGA Tour using ShotLink™, Mark Broadie, a business professor at Columbia University, was developing a unique way to analyze golfer performance using a program called Golfmetrics. This software was the first to use detailed strokes-to-hole benchmarks and was the first embodiment of strokes gained methodology.

The PGA Tour Benchmark

Strokes gained methodology began to take a more refined shape when Broadie gained access to ShotLink™ data, and he began to apply his Golfmetrics analytics to that massive database. With the quality and quantity of data provided by ShotLink™, Broadie was able to refine the details of strokes gained methodology, and created for the first time very accurate benchmarks based on millions of accurately recorded shots.

Strokes gained methodology works by first establishing strokes-to-hole benchmarks for a specified group of golfers. Broadie determined that the most significant factors for determining the number of strokes it takes to complete a hole are distance-to-hole and lie type. Using ShotLink™ data representing millions of shots performed by a group comprised of all PGA Tour players over the course of many years, Broadie determined the average strokes-to-hole from every distance-to-hole and lie type combination possible.

Once the benchmark is established, calculating strokes gained values for a shot requires a specific set of data for that shot: pre-shot distance-to-hole, pre-shot lie type, post-shot distance-to-hole, and post-shot lie type. Using this data, each shot can then be precisely compared to the benchmark for a given distance-to-hole and lie type. Exactly how strokes gained works will be described in detail below in the section called “How Strokes Gained Works“.

Shot Value

This statistic can be applied to value each shot individually in terms of strokes, gained or lost, to the benchmark, and cumulatively to assign a strokes gained over the entire hole, round, tournament, date range, specific shot category, or any specific range of golf shots desired. This can be done for any shot or defined group of shots on a golf course: any distance or distance range, any lie, any round or group of rounds. The spectrum of application to specific categories is virtually endless.

To those who understand it, strokes gained methodology produces statistics that are clearly superior to standard golf statistics, largely making them obsolete. It might be explained very simply this way: strokes gained measures every skill category in terms of the unit that determines the winner: actual strokes! In other words, every stroke can be valued, empirically, in terms of how many strokes it gained or lost to the benchmark, and these can be evaluated in the aggregate by almost any classification imaginable. This amounts not to just another statistical theory, but results in an actual quantifiable measure of each stroke.

There is little doubt that the strokes gained method of analysis will eventually dominate the landscape of golf statistics. Strokes gained methodology provides a powerful tool to analyze all elements of golfer performance, and a way to measure virtually any factor, including courses, clubs, weather, etc.

Implementation and Progress

However, the integration of strokes gained statistics into the world of golf has been surprisingly slow. On the PGA Tour, where ShotLink™ data is already collected and strokes gained analysis tools are already in place, the only statistic currently available is Strokes Gained Putting, which represents a small fraction of the statistics that could be made available. PGA Tour players and coaches do not have access to their personal strokes gained statistics other than Stokes Gained Putting, and golf analysts and the media have few tools to use the significant power of strokes gained to enhance commentary and analysis of tournaments.

Because the PGA Tour has been so slow to develop and promote strokes gained, the huge amount of people who view PGA Tour events on television are not educated about its value. Most people simply don’t understand how strokes gained works or why it is valuable.

Adoption By Amateurs

If they knew more about it, many golfers would desire strokes gained as an analytical tool for their own games. For most people interested in golf, Strokes Gained Putting is a stat they may be slightly familiar with, but generally strokes gained has been shrouded in mathematical mystery. But the truth is it isn’t complicated. Many are under the false assumption that strokes gained is impossible without ShotLink™ technology for collecting data, and therefore believe they could not have access to it without an army of volunteers showing up at their local course armed with lasers and trucks filled with computers. Strokes gained is generally viewed as a “professional statistic”. However, it will soon become clear that this type of game analysis has just as much to offer the non-PGA Tour golfer, if not more.

For the hordes of golfers who do not play in PGA Tour events, until now there has been essentially no access to “strokes gained” statistics. Prior to the creation of this website, a golfer interested in strokes gained statistics to measure aspects of his or her own golf game would be required to manually collect the necessary data for a game of golf and manually do the necessary mathematical calculations. While the data collection is relatively simple, the process of performing the calculations would be tedious and the results would be very limited (we know; we’ve done it).

Strokes Gained Golf occupies a unique and important place in the ongoing story of strokes gained and golf statistics in general. At SGG, we are dedicated to the idea that strokes gained statistics are extremely valuable to golfers of all levels, and it is our goal to make this uniquely valuable tool available to all golfers, in the most simple and painless way possible.