Dustin May Has Finally Discovered His Strikeouts

The quality of Dustin May’s raw stuff is undeniable. He throws his sinker with the highest average velocity of any starter in the majors and it’s ridiculous tailing action makes it one of the most GIF-able pitches in baseball. During each of his starts, Twitter is flooded with GIFs like this one.

Dustin May, Filthy Two Seamers.

Get out of my head, Joe Davis! (but, yeah, you're right ?) ? pic.twitter.com/gw5ZV2bxGk

— Rob Friedman (@PitchingNinja) April 15, 2021

It’s not just May’s sinker that stands out. His entire arsenal is composed of pitches with elite characteristics. Here’s a look at May’s repertoire and each pitch’s percentile ranks when compared with their respective pitch types:

May’s velocity on each of his pitches obviously stands out; he’s among the league leaders in average velocity on all four of his pitches. On three of his offerings, he has elite movement in one direction or the other. It’s a truly impressive arsenal without peer in the majors.

With such explosive raw stuff, you’d expect a correspondingly high strikeout rate. But heading into this season, May had only struck out 20.8% of the batters he’d faced during the first two years of his career. The talent was tantalizing, but the results just never quite followed. In March, my colleague Dan Szymborski picked May as one of his bust candidates for 2021, citing the same concerns over the disconnect between May’s stuff and his lack of strikeouts.

We’re just barely into May’s season but he’s looking like a breakout candidate rather than a bust. In three starts, he’s twice struck out eight with coming six in his other start for an overall strikeout rate of 33.8%. He’s continued to be stingy with free passes and his groundball rate is higher than ever. It really looks like May has figured out how to maximize the raw potential of his repertoire and turn it into actual strikeouts.

Heading into this season, he talked about how he wanted to hone his pitch mix so that he wasn’t so predictable with his sinker. When asked about what his approach will be this year, he told Mike DiGiovanna:

“Just being able to mix my pitches more. I’ve been so fastball dominant down in the zone with my sinker, and they kind of got a good idea of that — they know it’s my go-to pitch. So being able to mix some breaking balls down in the zone and flash some heaters up has been really good.”

The adjustments to his pitch mix have been noticeable during his first three starts.

He’s reduced the usage of his sinker and cutter, the two pitches that made up the majority of his pitches thrown in the past two seasons. He’s throwing his curveball more often — the breaking balls he spoke of in that quote above — and is also throwing more four-seam fastballs, too. It seems May is a man of his word; he’s executing the plan he laid out in spring training to the letter and it’s gone extremely well for him thus far.

It’s not just mixing in his curveball and four-seamer more often, though; he’s using his entire repertoire more effectively. When he’s ahead in the count, he’s throwing his breaking ball and his four-seamer more often than his other two pitches. Last year, once he got to two strikes, he threw his sinker 31.7% of the time. That pitch had the lowest whiff rate in his arsenal but he tried to use it to generate strikeouts anyway. This year, the two-strike usage of his sinker has dropped to 18.9% and he’s now using his curveball — with it’s 52.9% whiff rate — most often in those counts.

The effectiveness of all of his pitches has benefitted from an approach that isn’t so predictable.

Each of his pitches is running a career high whiff rate, driving his career high strikeout rate. We’re finally witnessing May figure out how to harness all his talent and stuff into phenomenal results.

May’s cutter in particular looks like it’s has taken a step forward this season. The 50% whiff rate on the pitch is a huge improvement over what he was generating in the past and the third highest among all cutters thrown at least 25 times this year. If you scroll back up to the table at the top of this article, you’ll notice that his cutter is the only pitch he throws that doesn’t possess elite movement in any direction. It’s not a sweeping or diving cutter, it’s a gyro cutter.

Seam-shifted wake is a new concept to pitching analysis that’s gaining plenty of steam since Hawk-Eye cameras were introduced across baseball, allowing Statcast to measure and record the spin axis of every pitch thrown without having to infer it using opaque mathematical means. Essentially, the idea is that seam-shifted pitches introduce a different type of spin to a pitch that affects the ball’s flight. A pitch’s spin direction will look one way out of the pitcher’s hand but the actual movement of the pitch when it crosses the plate suggests that the original spin direction was different.

There’s still so much we don’t know about this effect and the type of movement it creates. Tom Tango has shown that cutters in particular have a positive relationship with seam-shifted wake — the more gyro spin a cutter possesses, the more effective it is. When we measure spin direction, we can compare the spin direction out of the hand and the inferred spin direction based on the movement of the pitch when it crosses home plate. The deviation between these two measurements is a good proxy for measuring the effect of seam-shifted wake on a pitch.

Baseball Savant has introduced very handy graphics that show this deviation. Here’s the inferred (left) and observed (right) spin direction of May’s arsenal.

All of May’s pitches possess some amount of seam-shifted wake but his cutter possesses the most. The spin direction of that pitch deviates 75 minutes (using the clock as a proxy for degrees) on average. That’s tied for the second highest deviation among all cutters thrown at least 25 times this year. And perhaps more importantly, it’s an improvement of 30 minutes over what that pitch was posting last year. The overall spin rate of his cutter has fallen each year he’s been in the majors, from 2746 rpm in his debut to 2511 rpm this year. But the spin that is being imparted on the pitch is much more effective for that type of pitch. The result has been a huge increase in the pitch’s effectiveness in generating whiffs.

Dustin May’s arsenal is completely unfair. Each of his pitches possesses at least two elite characteristics. The only thing holding him back from reaching his potential was the know-how to utilize all of his pitches in the right way. It looks like he’s made the necessary changes to his approach to get the most out of each of his pitches while also greatly improving the effectiveness of his cutter. The Dodgers gave him a huge vote of confidence when they slotted him into the rotation to start the year, and they’re being rewarded for their faith in his talent. They don’t need another ace on their staff, but they finally might have one in May.