Are Walker Buehler's Run Suppression Wins Right? | MCUTimes

Are Walker Buehler’s Run Suppression Wins Right?

Walker Buehler has been in tears in the second half and led all pitcher in WAR since the All-Star break of 1.8, just a hair in front Adam Wainwright, Frankie Montas, and Max Fried. For the season, he now ranks fourth in the WAR among qualified starters (fifth if you include Jacob deGrom‘s 92 ridiculous innings), which was an expiration rate of 26.9% and a par-adjusted ERA 47% better than the league average. His 2.11 ERA is more than half a race better than any other season in his career, and the pair-adjusted figure is his best with 15 points. It’s another great season from one of the consistently best pitcher in the big ones; since becoming a full-time starter for the Dodgers back in 2018, Buehler has posted the 11th-most pitching WAR with the 19th-most innings hit.

I am not breaking any news by pointing out that Buehler has been and continues to be excellent. The numbers at the surface level indicate that he has never been better. What caught my eye, though, was how he has done it. There have been some noticeable changes under the hood. For example, at the age of 26, he has lost over a full cross in the speed of his fastball compared to any previous season; based on my own research, you would expect a player his age to only lose approx. 0.15 mph.

Buehler has also lost nearly two percentage points on his strikeout rate. On the face, it’s never something you’ll see in a pitcher if you lack smaller bats and lose speed. That said, he has brought his ground-ball rate back to pre-2020 levels, going from 35.5% last season to 43.8% this year, equivalent to his ’19 rate as well as a cross over the rest of the The league in 2021.)

It is reasonable to wonder whether Buehler has taken a small step back despite his excellent results, as players who lose speed year over year also generally lose efficiency in terms of race suppression and strikeouts. I took each season in the pitch tracking era for starting pitchers who threw at least 100 innings, then paired the seasons (each season should have 100 innings pitched), took the changes in speed, ERA, FIP and strikeout rate and mapped them. Here’s where Buehler falls in terms of speed drop:

Buehler’s speed change falls at the wrong end of all three curves. However, these curves describe the starting population in general so that he could attack hitters differently to compensate for his speed drop. Looking at thousands of jugs is not exactly conducive to potential edge cases.

That is not to say that he is not among the league’s elite; he is certain. What I would like to find out is whether Buehler is being supported by some battle team or if he has changed his approach at the expense of strikeouts. To that end, he has made some tweaks to his pitch mix, possibly in response to the lack of speed, leaning more towards his slider and cutter, as well as incorporating a change (mostly to the left) at the expense of his four-seams.

Buehler Pitch Mix

2018 3.7 8.0 40.7 13.8 18.6 15.2
2019 0.5 13.0 53.2 12.0 7.0 14.3
2020 0.0 12.8 53.9 17.4 7.7 8.2
2021 3.4 16.4 45.6 13.6 7.4 13.6

SOURCE: Baseball Savant

This change makes sense; his fastball has not been as effective an offer as it has been in the past.

The swing-stroke speed of Buehler’s fastball has steadily declined over time, hitting a nadir in 2021, even with more swings (as a percentage of the lanes) and more chases than last season. The curveball has also experienced a noticeable drop in performance across the board, and I wonder if this is a result of using his fastball less frequently and with less power as the curve tunnels out of it. The real gains for his arsenal have been the slider and the change, if the latter did not use at all in 2020, but has had fluctuating strikes out of almost 33% more than average. The shooter, meanwhile, has been particularly potent at evoking hunts.

Buehler also varies the places where he each throws his place. His zone rate has dropped a fraction of a percentage point from 2020, and his hunting rate has increased by 1.5%, a promising trend. He has also given strikes on the first pitch 65.7% of the time, going from slightly below the average last year to firmly above the league average. Using the Gameday zones defined by MLBAM (which you can find in the Baseball Savant search tool), you can see that Buehler throws a higher percentage of his lanes up into the zone (zones one, two and three), mostly with his four-sailors (an increase of 5.7 percentage points year on year) and cutters (10.6 percentage points) and has thrown several places down and off the plate, mostly with his shooter.

One thing that cannot be ignored, and which is probably behind both using four-seamer less and the pitch’s steep drop in sling speed, is a change in spin speed after enforcing the ban on sticky substances. Spin speed is partly a product of speed, so Buehler’s fall in this statistic this season should not come as a surprise. But even when you account for this ratio (by dividing spin speed by speed, which I will refer to as spin-velocity ratio, or SVR), the change is still visible.

Buehler SVR Evolution

Time period SVR
2018 25.1
2019 25.5
2020 26.4
2021 Before 3 June 27.6
2021 Since June 3 25.1

SOURCE: Baseball Savant

You can see a sharp drop in SVR right after reports surfaced that the enforcement of tacky drugs would begin in earnest on June 3rd:

This date is marked with the red dotted line; both intervals and averages at start-up began to decline after that time.

Most surprisingly, Buehler appears to have improved despite this. After a brief dip around the date on which enforcement was reported, his strikeout rate has steadily increased as the season has gone on:

Buehler’s adaptation to his repertoire after June 3 is even sharper than the changes from year to year, as he has accelerated his use of his groundbreaking orbits and changes:

Buehler Pitch Mix Split

Time period CH FC FF KC AND SL
2021 Before 3 June 0.7 12.4 50.8 15.3 8.8 12.0
2021 Since June 3 5.4 19.4 41.7 12.4 6.4 14.8

SOURCE: Baseball Savant

The same is true when shared with handiness, where he has relied more on his change to left-wingers (6.3% against left-wingers versus a lone change to right-wingers) and increased his use of the slider against right-handers to around 35%.

Buehler has improved as the season has gone on, even in light of his deterioration in spinning speed, and although loss of speed is never a positive development, he has compensated with increased use of his excellent pioneers as well as the return of his shift. He has also been helped by a .239 BABIP and a 9.9% HR / FB rate compared to a 13.0% mark before 2021. That mostly explains 1.02 gap between his ERA and FIP, the largest among qualified starters this season. Some of this ball fortune, however, should be attributed to Buehler; he has allowed numbers below average in terms of both barrel speed and hard-hitting rate, as well as a .340 wOBAcon versus a .370 rate for the rest of the league.

This .239 BABIP is a bit low, even for a pitcher showing great command, as is the home run rate, which is about a third lower than the average in the major leagues. But Buehler has localized in such a way that we should expect his results at contact with to be at least slightly below average. Combine that with a great strikeout rate and you have one of the best pitchers in the league. Is he a 2.11 ERA pitcher? Probably not, but he has shown the ability to adjust. It will be important if the Dodgers hope to avoid the dreaded wild-card game, win the NL West and defend their title.

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