Strokes gained: How it works

Strokes gained statistics have had a growing influence in the game of golf. That should continue with the introduction of three new strokes gained statistics: strokes gained: off-the-tee, strokes gained: approach-the-green and strokes gained: around-the-green. 

Along with strokes gained: putting, which was introduced in 2011, we can now analyze each aspect of a player's game with the strokes gained statistics, which compare a player's performance to the rest of the field. All strokes gained statistics are calculated using ShotLink, the PGA TOUR's real-time scoring system powered by CDW.

The strokes gained concept was initially developed by Professor Mark Broadie of Columbia University, utilizing ShotLink data that has been made available to academic institutions for research since 2007. Strokes gained is a better method for measuring performance because it compares a player's performance to the rest of the field and because it can isolate individual aspects of the game. Traditional golf statistics, such as greens in regulation and putts per green, are influenced by a player's performance on shots other than those being measured.

The PGA TOUR also produces strokes gained: total, which measures a player's performance against the field, and strokes gained: tee-to-green, which measures all strokes not taken on the putting green.

To explain how strokes gained can be used to analyze a player's performance, let's start with strokes gained: total. Strokes gained: total simply compares a player's score to the field average. 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.

In 2014, the PGA TOUR broke down strokes gained: total into two categories, strokes gained: tee-to-green and strokes gained: putting.

Strokes gained: putting measures how many strokes a player gains (or loses) on the greens. Strokes gained: tee-to-green measures all strokes not taken on the putting green.

Strokes gained: tee-to-green + strokes gained: putting = strokes gained: total

The new strokes gained statistics, which were introduced June 1, break down tee-to-green play into three categories: off-the-tee, approach-the-green and around-the-green. The sum of those three statistics equals strokes gained: tee-to-green.

Off-the-tee + approach-the-green + around-the-green + putting = strokes gained: total

Strokes Gained: Off-the-Tee
Strokes gained: off-the-tee measures player performance off the tee on all par-4s and par-5s. 

Strokes Gained: Approach-the-Green
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
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.

The strokes gained formula explained

Rickie Fowler made birdie on TPC Sawgrass' 18th hole in the final round of the 2015 PLAYERS Championship before winning the tournament in a playoff. Fowler hit his tee shot 330 yards on the 446-yard, par-4 before sticking his 116-yard approach shot 16 feet, 11 inches from the hole. He then made the birdie putt.

We'll use Fowler's birdie to explain how strokes gained statistics are calculated.

Tee shot: TPC Sawgrass' 18th hole is a 446-yard, par-4. The PGA TOUR's scoring average, or baseline, on a par-4 of that length is 4.100. Fowler hit his tee shot on No. 18 in the fairway, 116 yards from the hole. The TOUR scoring average from the fairway, 116 yards from the hole, is 2.825. He gained 0.275 strokes on his tee shot. Here's how:

Baseline for tee - Baseline for second shot - 1 = strokes gained: off-the-tee
4.100 - 2.825 = 1.275 - 1 = +0.275

One is subtracted from the difference between the two baselines to account for the shot that Fowler hit.

Approach shot: As noted above, the baseline from 116 yards in the fairway is 2.825. This is the average number of shots it takes a TOUR player to hole out from this distance. Fowler lost 0.001 strokes by hitting his approach shot to 16 feet, 11 inches. The baseline from 16 feet, 11 inches is 1.826. Here's how Fowler's strokes gained: approach-the-green were calculated for the shot.

Baseline for approach shot - baseline for putt - 1 = strokes gained: approach-the-green
2.825 - 1.826 = 0.999 - 1 = -0.001

Putt: Fowler gained 0.826 strokes by making his 16-foot, 11-inch birdie putt at 18. The TOUR baseline for a birdie putt of that length is 1.826, while the baseline for a holed shot is, of course, 0.

Baseline for putt - baseline for putt - 1 = strokes gained: putting
1.826 - 0 = 1.826 -1 = +0.826

A player's strokes gained statistics for the round are the sum of his strokes gained and lost on all 18 holes. Adjustments are made to account for a course's difficulty.

Baselines and probabilities

The PGA TOUR has calculated the average number of strokes needed to hole out from every distance and location on the course. These averages were calculated in one-inch increments on the greens and one-yard increments off the green and are used to create baselines of the average TOUR performance.  With the baseline as the foundation, the TOUR can calculate the probability of an outcome from any distance and location captured by ShotLink powered by CDW.

All shots captured by ShotLink powered by CDW are grouped into the following baseline categories:  tee, fairway, rough, sand, green, and other. “Other” includes all areas not already mentioned, such as native areas, dirt outlines, etc. 

Here are some fun facts revealed by this information:

Average shots to hole out (from the tee)
3.0 shots to hole out: 166 yards
4.0 shots to hole out: 410 yards
4.5 shots to hole out: 519 yards

Average shots to hole out (from the fairway)
2.0 shots to hole out: 7 yards
2.5 shots to hole out: 30 yards
3.0 shots to hole out: 168 yards

Players average about the same average number of shots to go from 70 yards in the rough (2.92) that they do from 150 yards in the fairway (2.92).

Players average just over three shots (3.01) from 170 yards in the fairway.  This is the same average from 100 yards in the rough (3.00).

The table below shows the average number of expected shots from 30 to 300 yards on the PGA TOUR. These values are shown from both the fairway and the rough.  “Fairway” includes both the fairway and the first cut of intermediate rough on both par-4s and par-5s. Rough includes only the primary rough on par-4s and par-5s.

The largest difference between the rough and the fairway occurs between 120 and 190 yards where scoring from the rough is on average about 0.25 strokes higher than those from the fairway. Holing out in three shots, if the first shot is an approach shot, would equate to a par.

Greens hit percentages

Distance from which players hit 75% of greens
From the fairway: 150 yards
From the rough: 47 yards
Difference: 103 yards

Distance from which players 50% of greens
From the fairway: 202 yards
From the rough: 148 yards
Difference: 54 yards

Distance from which players hit 25% of greens
From the fairway: 241 yards
From the rough: 203 yards
Difference: 38 yards

Distance from which players hit 10% of greens
From the fairway: 273 yards
From the rough: 238 yards
Difference: 35 yards

The table below shows the percentage of time a player hits the green from the fairway and the rough. This data is displayed in five-yard increments from 30 to 300 yards.

Up-and-down percentages

The below table shows the percentage of time a player gets up-and-down from the fairway versus the rough.  This data is displayed in 5-yard increments from 30 to 300 yards.  These calculations can be directly correlated to a player’s scoring probability from either the fairway or the rough. For example, a player hitting a second shot on a par-4 from 100 yards in the fairway has a 29% chance of converting birdie (holing out in two shots).

Up-and-down percentage
Up-and-down 33% of the time
From the fairway: 80 yards
From the rough: 38 yards
Difference: 42 yards

Up-and-down 25% of the time
From the fairway: 118 yards
From the rough: 56 yards
Difference: 62 yards

Up-and-down 10% of the time
From the fairway: 195 yards
From the rough: 144 yards
Difference: 51 yards

The below graph and table compares the percentage of time a player gets up-and-down from the rough and the fairway at various distances.

Expected putts and probabilities

The PGA TOUR has calculated the average number of putts taken to get the ball in the hole for every putt distance in one-inch increments. This calculation has been termed baseline or "expected putts."

With “expected putts” as the foundation, the TOUR can calculate the probability of a one-, two- or three-putt from any distance. The table below can be used as reference from various putting distances.

Putting probabilities
8 feet: Distance from which it's 50-50 whether a player one- or two-putts (1.5 average)
25 feet: Distance from which players one-putt 10% of the time
33 feet: Distance from which players average two putts
-- Note: 88% chance of two-putt, 6% chance of one-putt and 6% chance of three putt
40 feet: Distance from which players have a 10% chance of three-putting
64 feet: Distance from which players have a 25% chance of three-putting

It is estimated that players' chances of three-putting are not 50-50 until 120 feet. However, in general the greens on the PGA TOUR are not large enough to provide a player with a 50-50 chance of three-putting.