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Bringing Strokes Gained statistics to all golfers.

How Strokes Gained Works

How Strokes Gained Works

Strokes gained is a powerful advanced metric with far-reaching consequences in the golf world. There are numerous articles in major publications that address strokes gained and recognize it as a statistic that will change the way golf is played and understood. Unfortunately, those same articles portray the math behind the statistics as beyond the grasp of most normal people. There is an overwhelming perception that the strokes gained method is too complex for non-statisticians to understand.

However, you may be surprised to learn that strokes gained is really a very simple concept. The truth is, the process of generating strokes gained statistics is extremely intuitive, and the math involved is simple subtraction. Below, we will do our best to demystify strokes gained golf stats, showing step by step how they work. Hopefully, we can help you understand that while strokes gained is powerful, it is also simple. It is far-reaching in scope, but elegant and intuitive to create and use.

The Benchmark

The first concept to understand is the establishment of strokes-to-hole benchmarks. This is the key that unlocks strokes gained, and the work has already been done. These benchmarks are the average strokes-to-hole from every possible position and lie on a golf course, generated by a consistently performing group of golfers. The numbers have been determined with extreme accuracy by using ShotLink™ data, representing millions of shots performed by PGA Tour pros during real tournaments over the course of many years.

The benchmark numbers are simply the average number of strokes it takes PGA Tour pros to hole out from any position on the golf course. Every ball at rest is defined by the two most important variables for a golf shot: the distance-to-hole and lie type.

The result is a table with the average strokes-to-hole from 0-600 yards, for each lie type including tee, fairway, rough, sand, and "recovery" shots. A portion of the benchmarks table looks like this:

Distance Tee Fairway Rough Sand Recovery
           
10   2.18 2.34 2.43 3.45
15   2.29 2.47 2.48 3.48
20   2.40 2.59 2.53 3.51
25   2.46 2.65 2.60 3.54
30   2.52 2.70 2.66 3.57
35   2.56 2.74 2.74 3.64
40   2.60 2.78 2.82 3.71
45   2.63 2.83 2.87 3.75
50   2.66 2.87 2.92 3.79

This table shows the strokes-to-hole benchmarks for distances from 0 to 50 yards, for each lie type.

There is a separate table for putting, measured in feet rather than yards. A portion of the table looks like this, with 1-, 2-, and 3-putt percentages included:

Distance putts 1-% 2-% 3-%
         
1.00 1.00 100.0% 0.0% 0.0%
1.50 1.01 99.5% 0.0% 0.1%
2.00 1.01 99.0% 0.1% 0.1%
2.50 1.03 97.0% 2.5% 0.2%
3.00 1.05 95.0% 5.0% 0.2%
3.50 1.10 90.5% 9.5% 0.2%
4.00 1.15 86.0% 14.0% 0.2%
4.50 1.20 80.5% 19.5% 0.3%
5.00 1.26 75.0% 25.0% 0.3%
5.50 1.31 70.0% 30.0% 0.3%
6.00 1.36 65.0% 35.0% 0.3%
6.50 1.40 60.5% 39.5% 0.4%
7.00 1.44 56.0% 44.0% 0.4%
7.42 1.47 53.0% 46.5% 0.5%
7.83 1.50 50.0% 49.0% 0.5%
7.92 1.51 49.5% 50.0% 0.5%
8.00 1.52 49.0% 51.0% 0.5%

Calculating Strokes Gained For Each Shot

With benchmark tables firmly in hand, calculating the strokes gained value for a given shot is not at all difficult. The first thing to understand is that a strokes gained value is either positive or negative. A positive value means the stroke was better than the benchmark, and a negative value means the stroke was worse than the benchmark. The second thing to understand is that the value is in terms of strokes, or more precisely fractions of strokes to the hundredth. The third thing to understand is that in order to calculate the strokes gained value of a given shot, you need four simple but vital pieces of information: the pre-shot distance-to-hole, the pre-shot lie type, the post-shot distance-to-hole, and the post-shot lie type.

In order to make strokes calculation perfectly clear, we will use an example of a golfer on a course: let’s call him Tom.

Tom is standing on the tee box on the third hole of Big Duffer Country Club. He is playing the black tees, and tees off 430 yards from the hole. So we already know the vital pre-shot info:

  • Pre-shot distance-to-hole: 430 yards
  • Pre-shot lie type: Tee

A look at the strokes-to-hole table shows that 430Tee has a strokes-to-hole value of 4.05. So we know that on average a PGA Tour Pro takes just over 4 strokes to complete a hole of this length.

Tom hits his tee shot well, and his ball now rests in the fairway 140 yards from the hole. So now we know the vital post-shot data:

    • Post-shot distance-to-hole: 140 yards
    • Post-shot lie type: Fairway

Another look at the table shows a strokes-to-hole value of 2.91 for the new position.

To calculate the strokes gained value for the shot, we simply subtract using this formula:

(Pre-shot strokes-to-hole value) – (Post-shot strokes-to-hole value) – 1.00 = strokes gained value

So for Tom’s tee shot, we plug in the proper values so the formula looks like this:

  • (4.05) – (2.91) – 1 = (+0.14)

That is all there is to it. For his tee shot, Tom gained .14 strokes on the PGA Tour average, which makes sense since he hit the ball around 290 yards in the fairway.

On his next shot, Tom hits the ball from 140 yards in the fairway (2.91) to a greenside bunker, 15 yards from the hole. A look at the strokes-to-hole table shows that a ball 15 yards from the hole in the sand is 2.48. So for the shot from the fairway, the formula looks like this:

  • (2.91) – (2.48) – 1 = (-0.57)

Tom’s shot into the bunker was clearly poor, losing over half a stroke to the PGA Tour average.

On his next shot, Tom hits out of the bunker onto the green, 9 feet from the hole:

    Distance-to-hole: 9 feet
  • Lie Type: Green

The table shows that a ball 9 feet from the green has a strokes-to-hole value of 1.58. So for shot #3, the formula looks like this:

  • (2.48) – (1.58) – 1 = (-0.10)

Not a bad shot from the bunker, but Tom lost 0.1 strokes to the benchmark on that shot.

From nine feet, Tom runs his putt by and the ball comes to rest 3 feet from the hole. The new position on the green has a strokes-to-hole value of 1.05. The formula for the putt from 9 feet looks like this:

  • (1.58) – (1.05) – 1 = (-0.47)

Tom then sinks the 3 footer, with the formula looking like this:

  • (1.05) – (0.00) – 1 = (+.05)

Tom only gains .05 of a stroke for making the 3 footer, but it’s better than missing!

A simple table showing all five strokes for the hole looks like this:

Stroke 1 430T 140F +.14
Stroke 2 140F 15S -.57
Stroke 3 15S 9G -.10
Stroke 4 9G 3G -.47
Stroke 5 3G Cup +.05

We can see clearly that strokes gained can measure each shot. We can also see that strokes gained for the entire hole is -.95. This can be calculated two different ways. The strokes-to-hole value for 430 Tee is 4.05. Tom took 5 strokes to complete the hole: .95 worse than the benchmark. We can also just add up the strokes gained value for all the shots taken:

  • (+.14) – (.57) – (.10) – (.47) + (.05) = (-.95)

It is important to note that the strokes gained value for the hole does not measure how many strokes were gained or lost to par, but to the average strokes it takes a PGA Tour pro to put the ball in the hole of that length.

Calculating Strokes Gained for Groups of Shots

Beyond measuring the quality of individual strokes, strokes gained also has the ability to measure any aggregate of shots. For example, we can easily add up Tom’s strokes gained values for all shots taken during a 9-hole or 18-hole round. More importantly, we can carefully select a particular category to measure for the round. For example, we can add the strokes gained values for all strokes taken from a "green" lie type to get "Strokes Gained Putting" for the round. We can add the strokes gained values for all strokes taken from the tee on par 4’s and par 5’s to get a very useful "Strokes Gained Driving" statistic - a true measure of driving performance by which golfers may be ranked with scientific accuracy, unlike the traditional "Total Driving". We can essentially select any category of shots we like. Getting very specific, we could add the strokes gained values of all non-green shots between 0 and 75 yards. Potential categories that may be analyzed are virtually unlimited.

Tracking Strokes Gained Over Time

Recording strokes gained data for multiple rounds of golf leads to another exciting result: the ability to track change over time in any category. For example, you could see all of your strokes gained statistics in all categories for all rounds played over the course of a season or in the next few weeks or months after a lesson. This allows you to track progression and/or regression for any skill with precision. You can track your putting, driving, short game, or mid-irons precisely over time, knowing exactly where you have improved or where you have been worse. Gone are the days of guessing how well you are performing in a particular skill or distance range: now you can know exactly how well you are putting or driving from round to round. Now, instead of "feeling" like you are driving the ball better, the stats will show clearly and precisely how much better you are driving the ball in terms of how many strokes it has actually gained you. This information can be used to plan practice time more effectively, as well as make each shot a little more interesting. You may have a day when much of your game is below average, but you are putting so well that it keeps your motivation going during a round, knowing that the stats will show an outstanding day of putting. In other words, rather than ending a round with one score to measure your game, you can simultaneously be playing multiple "games within the game".

Creating New Benchmarks

With enough amateur data, custom benchmarks can easily be created for friends, particular handicap levels, for yourself, or a number of other interesting measures. The core statistics resulting from strokes gained analysis essentially compare each of your shots to the average result expected from PGA Tour pros from the same position. For most of us, this may seem like a daunting proposition. For most of us, the vast majority of our shots are not likely to look good in comparison. However, you may be surprised at how many shots you hit during a round that are better than the PGA Tour average. It is a very nice feeling to know that you just hit a shot or a putt of PGA Tour quality! A few of these shots each round are what keep us coming back to the game. You could even award the best shot during a round played with friends, without having to be subjective, by simply observing which shot gained the most strokes.

In addition, strokes gained analysis allows you to compare yourself not only to Tour Pros, but to anyone you like. For example, you can see how each shot compares to a 10 handicap or a 20 handicap player. In other words, strokes gained easily allows for comparisons to any other player or group of player: the PGA Tour benchmark is only the raw, initial source of comparison. So while the numbers will always show you how you stack up to the highest quality golf, they can simultaneously show you how you stack up against a friend or a person of a given handicap level.

In addition, you will always be able to compare you shots or you rounds to your own level! You can know with precision whether any shot was better or worse than your own average for a given category. This is a very useful tool for measuring your progress.

Targets

Strokes gained statistics and benchmarks also allow for the unique ability to establish various targets for any shot. For example, standing over a shot from the fairway, 150 yard to the hole, strokes gained benchmarks can immediately tell you where a pro would be expected to hit the shot, where a 10 handicapper would be expected to hit the shot, or where you would be expected to hit the shot. Similarly, after hitting a shot, you can know precisely the quality of the shot in terms of what player would be expected to get that result. For example, you can know if the shot you just hit was a Rory McIlroy level shot, a scratch golfer level shot, or a 30 handicapper level shot. This has the potential to change the way you look at the game of golf, and may help you concentrate on the importance of the shot at hand. Knowing precisely the quality of each shot naturally leads to a habit that most golfers are trying to build: focusing on the shot at hand. Strokes gained analysis helps you do this by offering a way to precisely measure the quality of each shot.

Your Strokes Gained "Handicap"

Your official handicap is determined by considering your last 20 rounds of golf. Strokes gained has the ability to closely parallel the handicap system by measuring your strokes gained value in any category by averaging your last 20 rounds. In this way, you have a way to measure your current overall skill in any category, in the same way that a handicap measures your current golf level overall. In this way, you can know that right now you are, for example, a -3.23 putter, a -0.53 in the 0-50 yard range, and a +0.38 driver. Or, viewed in another way, you might putt like a typical 20-handicapper, have the short game of a 4 handicapper, and drive like a scratch golfer. In other words, you can keep a “strokes gained handicap” for every skill that changes over time just like your handicap changes over time.