Tiger Woods ace in the hole

His dominance of this hallmark measurement was both a key to the 2018 success of Tiger Woods and on par with some of the best performances of the Strokes Gained era

The hallmark of Tiger Woods’ 2018 return to prominence was his season-ending leadership of the game’s single most decisive analytic, Strokes Gained Approach Shots.

Based on regression analysis of all PGA Tour players completing enough rounds to qualify for consideration since the Strokes Gained measurement was introduced in 2004, the relationship between a player’s performance in Strokes Gained Approach and his scoring average is -0.70 on a scale where zero indicates no relationship and -1.0 indicates a perfect relationship.

That’s a strong relationship, and similar to the -0.69 relationship for the 2018 season alone..

What does that suggest? It suggests that Woods’ Tour-best 0.938 score in Strokes Gained Approach was a major contributor to his 69.35 stroke average, the seventh lowest on Tour.

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But it prompts a second question: how did it rank with other great performances during the Strokes Gained era? To accurately make that determination, we can’t just look back at the tables and count how many players have posted Strokes Gained Approach scores better than 0.938. As with the other Strokes Gained measurements, far too many variables play into Strokes Gained Approach. Year-to-year equipment changes, the ever-changing roster of players – with their divergent skill sets – weather and the changing panoply of courses would combine to invalidate such a simplistic approach.

In any kind of comparison over time, what is needed is a relativistic statistic that factors in – neutralizes might be a better word – all the year-to-year changes that would otherwise complicate such a comparison to the point of hopelessness.

There is such a tool: standard deviation. Because standard deviation measures the relative excellence of any performance against a fixed set of competitors under the same course and weather conditions, it provides the required neutrality.

The key is this: Instead of asking how Woods’ 2018 Strokes Gained Approach score compared with others, we need to ask whether it was more or less exceptional – compared with his 2018 competitors – than were scores posted in previous seasons.

Measuring exceptionality is not a complicated practice; in effect, what we’re doing is aligning every competitor in every individual season along a gigantic bell curve, and seeing who winds up farthest out on the edge. In any set of data – such as the Strokes Gained Approach totals for 193 PGA Tour pros in 2018 – about two-thirds will wind up within one standard deviation of the field average. Most of the rest will fall within two standard deviations of the average, while a handful – maybe two or three percent – will stand outside the two standard deviation barrier. That’s not my rule, it’s math’s rule.

By the way, those placings can occur on either the good or bad side of the curve.

In 2018, two of the 193 pros exceeded the 3 standard deviation performance barrier – and both fell on the bad end of the bell. With a -1.586 Strokes Gained Approach, Daniel Summerhays was 4.47 standard deviations below the field average of +0.06, one standard deviation equaling 0.37 strokes in 2018. Greg Chalmers’ -1.192 Strokes Gained Approach translated to -3.40 standard deviations worse than the field average.

Eight other players – Woods among them at 2.39 — fell outside two standard deviations. Others more than two standard deviations to the good side of the statistic in 2018 Keegan Bradley (0.924, 2.35), Justin Thomas (0.88, 2.23), Henrik Stenson (0.86, 2.23) and Dustin Johnson (0.851, 2.15)

Aside from Summerhays and Chalmers, the three players more than two standard deviations below the Tour average in Strokes Gained Approach were Cody Gribble (-.696, -2.05), Martin Piller (-.811, -2.37) and Matt Atkins (-1.039, -2.99).

Among the 25 best Strokes Gained Approach scores – as measured by the standard deviation of their exceptionality compared with that year’s field average – six also led the Tour in scoring average during those seasons. The average rank of the top 25 in stroke average was 8th, only five of the 25 finishing outside the top 10 in stroke average for the season in question. Tiger’s 2018 performance, by the way, ranks in a tie with Jim Furyk’s 2006 score for the 25th spot.

Here is the full list of 25 most exceptional seasons as measured by the standard deviation of each player’s performance in Strokes Gained Approach:

Season Name SG Approach St. Dev.

2006 Tiger Woods 2.072 4.74
2007 Tiger Woods 1.653 4.28
2013 Tiger Woods 1.533 3.62
2009 Tiger Woods 1.398 3.52
2016 Adam Scott 1.491 3.47
2015 Henrik Stenson 1.244 3.26
2008 Robert Allenby 1.217 2.99
2014 Jim Furyk 1.175 2.99
2012 Tiger Woods 1.224 2.98
2010 Adam Scott 1.164 2.93
2014 Sergio Garcia 1.150 2.92
2004 Sergio Garcia 1.211 2.83
2015 Jim Furyk 1.081 2.81
2011 Luke Donald 1.094 2.79
2004 Vijay Singh 1.116 2.59
2014 H. Matsuyama 1.022 2.56
2015 Paul Casey 0.991 2.56
2009 Steve Stricker 1.018 2.52
2009 Robert Allenby 1.015 2.51
2011 Chad Campbell 0.987 2.51
2007 Ernie Els 0.994 2.50
2006 Adam Scott 1.115 2.46
2010 Vijay Singh 0.979 2.44
2012 Rory Mcilroy 1.002 2.42
2018 Tiger Woods 0.938 2.39
2006 Jim Furyk 1.085 2.39

With that method as a measuring stick, it becomes easy to contextualize Woods’ 2018 performance approaching the green relative to all others since 2004. And let it first be noted that Woods himself is the dominant figure on such a list. His 2018 performance marks his sixth inclusion among the all-time top 25 in Strokes Gained, and he holds the top four positions. Those factoids alone legitimize the importance of Strokes Gained Approach.