Understanding ‘Strokes Gained’ in Golf Betting

A history of strokes gained

Much like expected goals (xG) in soccer, strokes gained was an almost unheard of concept amongst golf fans up until very recently.

However, the ever-increasing demand from serious bettors and pundits alike to see past subjective narrative and embrace raw underlying data has seen the strokes gained metric sky rocket in popularity in recent times – with the term now fully embedded in mainstream golf’s lexicon.

First officially adopted by the PGA Tour back in 2011, strokes gained was created by Mark Broadie, a Columbia Business School professor. Strokes gained started out life as a mere putting stat, before quickly evolving to encompass the whole course.

Sometimes referred to as the “strokes gained guru”, Broadie recognised that the traditional method of assessing a golfer’s performance lacked nuance and context.

Prior to the age of laser technology in golf, traditional golf stats such as fairways and greens in regulation as well as total putts and one putt percentage were the best fans and players could hope for when evaluating play and making predictions.

Much of this method was simple counting, however Broadie (like other golf analysts) recognised a fundamental problem with this method, namely that it was misleading and overly simplistic.

For example, a count of fairways in regulation wouldn’t distinguish between a big miss (out of bounds) and a small miss (in the rough).

While a count of putts wouldn’t distinguish between a two-putt from 60 feet (a good performance) and a two-putt from two feet (a horrible performance).

Beginning nearly two decades ago, Broadie’s determined and pioneering research has gifted golf bettors with a detailed way of accurately assessing player performance. So, what exactly is stokes gained and how does it work?

What is strokes gained?

Strokes gained is a zero-sum calculation for every professional golfer on a tour that measures each golfer’s performance against their fellow pros of various skill levels.

Using strokes gained, bettors can understand what type of player they’re studying and how their particular skills align with whatever course they’re playing on.

A golfer’s strokes gained is calculated by subtracting his/her score from the average score of all the golfers who played that particular round – meaning that a player that has positive strokes gained for a round scored better than the average of all players who played that round.

This in turn helps golfers, pundits, and bettors figure out where they’re losing (or gaining) strokes as it not only measures a player’s performance against the rest of the field, but also provides an isolated view of specific aspects of their game.

Similar to expected goals (xG) in soccer, strokes gained quantifies the quality of each shot relative to what would be expected by an average PGA Tour professional.

Naturally relying heavily on historical data, statistics from tournaments of old are accessed via ShotLink – the PGA Tour’s official shot-level data collection system.

Since 2003, the PGA Tour has used laser technology and about 350 volunteers at each event to record detailed information on every shot taken at its tournaments.

Free to access for anyone, the ShotLink database contains detailed information on more than 11 million shots. Unlike systems based on GPS, the 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.

In his book Every Shot Counts, Broadie gives this brief explanation of how his strokes gained measurement works in practice:

“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.”

The different types of strokes gained statistics

Since its inception, the strokes gained formula has continuously developed – and is now at a point where it’s comprised of four different measurements for various parts of the course.

Each aspect of a hole of golf is measured, calculated, and then added in a formula to get the overall strokes gained total. The overall strokes gained total would then be represented in one figure.

For example, a player will gain three strokes on the field if he shoots 69 on a day when the field averages 72. A player who shoots 74 on that day loses two strokes to the field.

Similarly, bettors can study the individual measurements if they want to assess a specific aspect of a player’s game.

The total strokes gained calculation is as follows:

Off-the-tee (SG:OTT) + approach-the-green (SG:APP) + around-the-green (SG:ARG) + putting (SG:PUTT) = strokes gained total

Strokes Gained: Off-the-tee

Measures player performance off the tee on all par 4s and par 5s.

Strokes Gained: Approach-the-green

Measures player performance on approach shots. Approach shots include all shots that are not from the tee on par 4 and par 5 holes and are not included in strokes gained: around-the-green and strokes gained: putting. Approach shots include tee shots on par 3s.

Strokes Gained: Around-the-green

Measures player performance on any shot within 30 yards of the edge of the green. This statistic does not include any shots taken on the putting green.

Strokes Gained: Putting

Measures how many strokes a player gains (or loses) on the greens.

Strokes Gained: Tee-to-green

All shots that were taken from the tee box until a golfer reaches the green.

According to research by Data Golf, the predictive hierarchy of the strokes-gained categories appears to go OTT > APP > ARG > PUTT.

This means that golfers who are gaining their strokes with the long game, as opposed to the short game, will be expected to show less regression to the mean in their performances going forward into the future.

The differences in predictability across the strokes gained categories allows for improvements to be made over a pure total strokes gained model.

How can strokes gained be used in betting?

Strokes gained is simply a must-use for any bettor looking to evaluate player quality, and in turn, make predictions for various tournaments.

Unlike Official World Golf Rankings, FedEx Cup points or money list standings, all which are too superficial a measurement tool to use when making golf predictions, strokes gained is a detailed consideration of each and every shot a player makes – assigning a true value to each and every player.

With the possible exception of tennis, golf is unique in professional sports due to how venue-dependant the game is – with the choice of venue often massively influencing the final outcome.

Some courses will favour a golfer who can hit the ball a long way off the tee, some courses will suit players with more accurate approaches – while others will have challenging greens where only excellent putters will prosper.

Using strokes gained, bettors can understand what type of player they’re studying and how their particular skills align with whatever course they’re playing on.

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