Tuesday, April 1, 2014

Golf stats revolution : the gained strokes concept !

I’ve just finished a fascinating golf book on golf statistics called “Every Shot Counts: Using analytics to improve your golf performance”.


Don't stop here and continue reading as these kind of statistics are not boring at all !
This book might be a revolution helping golf players to really estimate their golf skills and improve their performance!
I will share with you the calculations I made hole by hole compared to a PGA Pro and therefore try to understand which part of the game we could improve! 
The concept of "stroked gained" in golf has been introduced by Mark Broadie, professor at the Columbia Business School of New-York, who first calculated the average putting strokes gained  by a player compared to the average field of players in a PGA tournament, this indicator helping to illustrate whether a golfer was beating the field at putting or not... 
Example of putting strokes gained: a stroke gained indicator of +1.2 would simply mean that the player putted 1.2 strokes less than the average field of players on 18 holes while an indicator of -2.0 would mean that the player putted 2 strokes more than the average PGA Tour field on 18 holes. This indicator therefore reflects the putting performance of one player compared to the field.   

The stroke gained was recently adopted as a new stat by the PGA Tour which represents a big achievement for his creator and praobably a big step forward in term of golf stats for the whole golfing community!
Measuring the putting performance is important but however not sufficient to explain the global performance of a golfer. This explains why the author also developed the concept of strokes gained for shots outside the green: gained strokes for driving as well as gained strokes for the short and long game. 
Based on a simple table to fill on every hole played, I recently managed to implement the calculation of the exact gained/lost strokes for every shot.
Table to fill on each hole:

Results reported after the golf round on an xls sheet including Pro average and the calculations

Column1: represents the position of the ball from the pin/flag measured in yards (measured with a laser range finder or marks indicated on the fairways) and feet for putts on the green.

Column2: club played.

The position of the ball indicated in column3 (tee, fairway, rough, sand, recovery shot or green) will have an influence on the average strokes of the PGA player (column4 of the table), the average of shots to putt the ball in the hole being be more important as the ball stands in the rough, in the sand or for a recovery shot (from the woods for example) than on the fairway.

The average strokes PGA reflected in column4 represents the data collected by the author of the book and will help to calculate the strokes a player would gain/lose against the pro.

The strokes gained (positive number) indicator or lost (negative number) compares the one stroke I need to move the ball forward to the average strokes needed by a PGA player to move the ball from the same position.

On the first hole, a drive from 498 yards would result in an average score of 4.41 strokes for a PGA professional while the next position from 260 yards would result in a score of 3.58. The difference of 0.83 strokes between these two numbers (see column6, 4.41-3.58=0.83) is then compared to the 1 stroke I need to move the ball to the same position.

I therefore only lost 0.17 strokes (0.83-1=-0.17) for that good drive on the fairway compared to a golf pro  (column8).

The lost stroke of -0.17 is however minor  and is a good result compared to the missed shot only moving the ball from 165 to 106 yards as the latter would result in 1 full stroke lost (-1.01, hole 1, column8 )! 

These two examples solidly illustrate that a good/bad shot can now be mathematically measured !

Here below the conclusion of the entire round:

Based on the table above, the putting only represents 18% of the total lost strokes while the long game (drive + shots >165 yards) represents almost half of all lost strokes (47%). Working on the long game seems to be worth it as 10.2 stroked separates me from the pro on that part of the game ;-).

This table also indicates an excellent putting on the back nine as only 0.5 shot was lost compared to a pro which is a level pro putting !







No comments:

Post a Comment