Measuring Dustin Johnson’s dominance at the Northern Trust

NORTON, MASSACHUSETTS - AUGUST 23: Dustin Johnson of the United States celebrates with the trophy after going 30-under par to win during the final round of The Northern Trust at TPC Boston on August 23, 2020 in Norton, Massachusetts. (Photo by Maddie Meyer/Getty Images)
NORTON, MASSACHUSETTS - AUGUST 23: Dustin Johnson of the United States celebrates with the trophy after going 30-under par to win during the final round of The Northern Trust at TPC Boston on August 23, 2020 in Norton, Massachusetts. (Photo by Maddie Meyer/Getty Images) /

Where the 30-under victory by Dustin Johnson ranks among the top performances in Tour history.

Dustin Johnson’s 11-stroke victory at last week’s Northern Trust was obviously remarkable. But how remarkable was it from a historical perspective? How many, if any, better single tournament performances have been authored in PGA Tour history?

As usual, the Tour record book – seasoned with a bit of math – provides answers. They’re not complete answers, but they do help to put Johnson’s 30-under week in some meaningful perspective.

Let’s start with the short term. Both by score, margin of victory, and standard deviation – the top tool for measuring exceptionality – Dustin Johnson’s week was the best enjoyed by any PGA Tour player this season.

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The 30-under by Dustin Johnson set the season-high for strokes under par previously held by Andrew Landry in winning the American Express at 26-under back in January.

His 11-stroke advantage over runner-up Harris English also bettered the season’s previous largest margin of victory, six strokes by Joaquin Niemann at the first event, the Military Tribute at the Greenbrier. Niemann finished that far ahead of runner-up Tom Hoge.

In doing so, Niemann had also set the season standard for the best standard deviation from the field. At the Greenbrier, he was 3.61 standard deviations superior to the field of players completing four rounds. In Boston, Dustin Johnson beat the four-round field average by 4.09 standard deviations.

By any of those measures, it is possible to find historical precedents that exceed Johnson’s week. But you to do some digging.

The PGA Tour record book identifies 15 players who have won a tournament by margins exceeding Dustin Johnson’s 11 strokes…none, by the way since 2006. Phil Mickelson was the last to do so, claiming that season’s Bell South Classic by 13 over Jose Maria Olazabal.

Mickelson shot rounds of 63-65-67-65 over the par 72 Duluth, Ga. Layout, finishing at 28-under. That put him 4.54 standard deviations ahead of the field, making it the most dominant one-week performance for which we have full data in Tour history.

A standard deviation is a superb tool for measuring dominance because it normalizes all the necessary week-to-week adjustments – in course layout, field strength, equipment, weather, and the like – that would otherwise make meaningful cross-time comparisons of golf results nigh onto impossible.

Among the winning margins that were larger than Johnson’s, certainly the two most memorable are those authored by Tiger Woods: his 15-stroke victory at the 2000 U.S. Open at Pebble Beach and his 12-stroke win at the 1997 Masters.

Woods’ 2000 U.S. Open win at Pebble Beach came by a margin of 4.34 standard deviations ahead of the field, making it slightly superior to Johnson’s week. When Tiger won the 1997 Masters, he did so by a margin of 3.20 standard deviations. That’s also excellent, but not as excellent as Johnson.

The record for margin of victory is 16 strokes. It’s been done four times, although not since Bobby Locke at the 1948 Chicago Victory Open. The others were J Douglas Edgar at the 1919 Canadian Open, Joe Kirkwood Sr. at the 1924 Corpus Christi Open, and Sam Snead at the 1936 West Virginia Closed Pro.

PGA performance records are only partial prior to 1970, but it is possible to comparatively assess one of those 16-stroke margins relative to Dustin Johnson by use of newspaper records. When he won the 1948 Chicago Victory Open at Midlothian Country Club, Locke shot an 18-under par 266 to beat Ellsworth Vines by that 16-stroke margin.

The field average that week on the par 71 layout was 293.61, with a gaping standard deviation of 9.75 strokes. That left Locke just 2.83 standard deviations ahead of the field.

The massive standard deviation – nearly double the standard deviation at the Northern Trust last week – suggests a largely non-competitive field whose relative weakness tempers the enthusiasm that might normally build around somebody going as low as Locke did. Dustin Johnson, by contrast, reigned over a far deeper, stronger field.

At the 1975 Phoenix Open, Johnny Miller shot 67-61-68-64 for a four-round total of 260 that was 14 strokes better than Jerry Heard’s runner-up 274. Miller finished 4.41 standard deviations ahead of the field, the most dominant performance for which we have a record since Locke’s 1948 win at the Victory Open.

Jose Maria Olazabal shot 262 to win the 1990 NEC World Series by a dozen strokes. But that was a limited-field event, and due to lack of depth, those tend to produce less competitive fields. Indeed, although Olazabal’s winning margin at the 1990 NEC was one stroke more than Johnson’s at the Northern Trust, the standard deviation of his week was just 3.94, making it fractionally less impressive.

In terms of raw score, the only two other 30-unders on record were by Ernie Els and Jordan Spieth at the 2003 and 2016 Tournaments of Champions. Again, though, the impressiveness of both is tempered by the small field size. Els’ win only translated to 2.64 standard deviations better than his peers, while Spieth rose only to 2.52.

Next. Northern Trust: Dustin Johnson continues roller coaster season. dark

Here’s the bottom line. Dustin Johnson’s win may not have been the most historically dominant on Tour, but it’s in the discussion.