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What’s Changed – Zach Johnson

This week the Tour travels to Illinois for the John Deere Classic, a birdie-fest notable for the poor field it attracts in advance of next week’s Open Championship in Scotland. After winning last season, Zach Johnson has been installed as the second favorite by bookmakers and fantasy columnists, behind 2009-2011 champion Steve Stricker and ahead of Louis Oosthuizen and Keegan Bradley. This on its own is not particularly notable; past champions who also happen to be good players are considered favorites at most events, especially when the John Deere field contains only four of my top 25 players by both Z-Score and OWGR. What is particularly strange here is that Zach Johnson has been thoroughly mediocre so far this season. After a four year streak from 2009-2012 that marked him as a consistent top 25 player in the world by Z-Score (between -0.62 and -0.35 all four seasons), he’s fallen off precipitously to -0.13 over 51 rounds. Now, golfers play more poorly than normal over half seasons due to plenty of factors ranging from random variation to injury to genuine deterioration of skill. I’m not as concerned about whether Zach Johnson will continue to play well below his career average as I am interested in just why he’s playing so poorly this year and which parts of his game are responsible for the regression.

First, I will examine what made Johnson such a prolific player in past seasons, specifically focusing on 2012. This analysis will be using the Strokes Gained method, breaking down shots into Putting, Driving, Approach shots, and Scrambling shots. For this, I’ve created Strokes Gained – Driving, Strokes Gained – Approach Shots, and Adjusted Scrambling using publically available PGA Tour stats, and will use the PGA Tour’s own Strokes Gained – Putting stat. I have already explained how my Adjusted Scrambling stat is calculated; the other two will be introduced in coming weeks. For now, it’s important to know 1. the stats are measured in strokes above and below the field and 2. I try to isolate how well a golfer is performing in one area by adjusting for distance of shot, starting position, and what happens in subsequent shots.

Zach Johnson’s 2012 was a great season. He ranked 20th in the world according to my Z-Score Method, won two tournaments, earned four other top tens, and missed only a single cut. His success was driven by great putting and approach shots – he ranked 5th and 7th in those metrics, saving a total of 1.4 strokes relative to the field. His tee shots were a weakness, but cost him less than 0.1 strokes. He made up an equal number of strokes by scrambling well above-average, which combined with his great putting kept him out of bogey trouble when he missed the green. In short, he was as efficient as all but the most elite (Tiger, Rory, Adam Scott) golfers, performing well in three areas, while minimizing his losses in the weakest part of his game.

This season everything has gone off the rails. Starting with his approach shots, Johnson has fallen from 5th to barely above-average, and that’s the only part of his game that has even been above-average. He’s never rated highly in Greens in Regulation because, as a very short driver, he faces longer approach shots. Because of that it’s hard to get a sense of a decline in this area just by looking at the normally cited stats (he’s actually improved his GIR rank from 2012). In 2012, his approach shots yielded 2.72 expected birdies (sum of the probability that a birdie putt will be holed based on its distance). This figure ranked 45th on Tour, despite Zach Johnson hitting his approach shots from much further distances than most of the elite players. This year, he’s ranked only 112th.

More damaging has been his putting. Johnson was 7th on Tour in Strokes Gained – Putting in 2012, gaining 0.6 strokes on the field per round just from putting. For whatever reason, Johnson has really struggled on the greens this year and has essentially been average, losing 0.04 strokes versus the field this year. That itself is stunning. He had scored seasons of 0.38, 0.58, 0.57, and 0.60 strokes gained/round since 2009, and suddenly looks no different than the average Tour golfer at putting. I can speculate about all sorts of reasons for this decline – less practice, less preparation, age related yips, etc. – but obviously this is a huge problem. Johnson cannot return to his old form without regaining his putting stroke. Plenty of guys (Vijay, Adam Scott, Lee Westwood) are or have been great players despite not being good putters, but they’re fantastic tee-to-green players. Johnson needs to compensate for his inability to drive the ball far.

Johnson’s has struggled scrambling this year, but not to the point where it’s costing him more than a few hundredths of a stroke/round, and his driving hasn’t noticeably changed. But it’s apparent that all the decline we’re seeing from Zach this year is due to his inability to generate good looks for birdie and to putt at an elite level. I’d certainly bet on him regaining his form – he’s still only 37 and has extensive history of high level play – but I think it’s crazy to consider him a better player at this point than Keegan Bradley or Louis Oosthuizen.