On the Dodgers’ declining spin rate since MLB’s crackdown

Major League Baseball began its enhanced enforcement of banning foreign substances on baseballs on June 15, and most of what we’ve seen over the last week plus is the visual of an umpire checking a pitcher after he walks off the field — for starters, multiple times per game; for relievers, at the end of the inning in which they enter the game.

When one of those inspections came as Clayton Kershaw was walking off the field to a standing ovation after his 13-strikeout, eight-inning gem on Sunday, he joked with home plate umpire Ryan Blakney.

“I told him ‘You might get booed here for a little bit’,” Kershaw said. “It’s part of the game now. They’re just doing their job. They’re doing what they’re asked to do. You just kind of roll with it and keep going.”

As for how teams are rolling with it, Rob Arthur at Baseball Prospectus looked at spin rates throughout the league this season, and since the enforcement memo from MLB went out to teams — which Arthur defines as May 15 — the Dodgers have the largest drop in spin rate among all teams, down roughly 200 rpm.

The Dodgers lead MLB in spin rate by a wide margin this season. The poster boy for this is Trevor Bauer, who has long pointed out the prevalence of foreign substances in increasing spin rate, while also seeing his own spin rates dramatically increase after 2019.

“I just want to compete on a fair playing field. I’ll say it again. That’s been the point this entire time, that everyone can be on a fair playing field,” Bauer said on June 6. “So if you’re going to enforce it, enforce it. And if you’re not, then stop sweeping it under the rug, which is what they’ve done for four years now.”

Once the enforcement started, Bauer said of MLB, “They didn’t get a whole lot about this right.”

When a report from Sports Illustrated in early June noted that the Dodgers had the largest increase in spin rate in 2021 compared to 2020, and with the pending MLB crackdown on the horizon, manager Dave Roberts told reporters in Atlanta, “Once things are implemented, then we’ll adhere to the rules. That’s the way we should all look at it.”

Bauer’s not the only reason for the Dodgers’ increase in spin over last year. The club also added Jimmy Nelson, Garrett Cleavinger, and Alex Vesia, and jettisoned low-spin pitchers Pedro Báez, Dylan Floro, and Adam Kolarek.

Arthur notes that the Dodgers since May 15 had the biggest spin rate decline and the biggest spin-to-velocity ratio (SVR) decline, with an interesting wrinkle about Bauer:

The league as a whole is down around 0.7 SVR in the last two weeks compared to the pre-memo era (which I’m defining as beginning May 15, the day spin rate began to fall). The Dodgers, by comparison, are down around 1.3 SVR, almost double the league average effect. They’re still tops in baseball even after the crackdown, but instead of being well beyond every other club, they’re fairly close to the second-place White Sox.

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But Bauer is hardly the only offender on the Dodgers, as it turns out. In fact, even if you exclude Bauer entirely from the team’s statistics, they still boast both the highest SVR and largest decline in SVR in the league. Each of the main Dodgers rotation regulars with playing time in 2020 and 2021 saw a somewhat significant bump (often coupled with decreases in velocity, which ought to reduce spin). Bauer isn’t driving these patterns, at least not directly.

Before May 15, the Dodgers had a 3.40 ERA and 3.56 FIP, a 27.6-percent strikeout rate and 7.6-percent walk rate, all ranking in the top five in MLB. Since then, even with the declined spin rate, Dodgers pitchers have a 3.13 ERA, 3.66 FIP, 28.1-percent strikeout rate and 8.6-percent walk rate.

That brings to mind a quote from pitching coach Mark Prior, on the eve of MLB’s official foreign substance enforcement period starting, from Bill Plunkett at the Orange County Register.

“If things do change then we adjust. That’s part of the game anyway. We adapt,” Prior said. “You always have to go through adjustment periods on a lot of things – whether teams are adjusting to how we’re pitching them, whether our guys aren’t pitching to the best of their ability at certain times.