Grant Dayton, Fastball Spin Rate, and How It Applies to the Yankees

I was listening to the episode 56 of The Ringer MLB podcast on my way to work yesterday, in which hosts Ben Lindbergh and Michael Baumann interview Dodgers reliever Grant Dayton. If you have no clue who Dayton is, don't fret. He made his major league debut as a 28 year-old last season and pitched in only 25 games. Yet, Dayton was fantastic in that short time. He boasted a 2.06 ERA and an elite 38.6% strikeout rate (13.33 K/9). His numbers in the minors were similarly spectacular. This year, the Dodgers will count on him to be a bridge to closer Kenley Jansen. And rightly so, because Dayton certainly looks like an elite reliever.

Alright, so where am I going with this? This isn't a Dodgers blog, after all. Hold on for a few more paragraphs - we'll get to how this relates to the Yankees.

If you haven't listened to the Dayton interview, I recommend it. He discusses his success and how effective his fastball has been for him. Though it averages 92.2 MPH, it plays up because Dayton is well aware of its above average spin rate. What can spin rate do for a pitcher? Very good things on the high end of the spectrum. A higher spin rate on a fastball induces more fly balls and whiffs, as Mike Petriello of explains.

Chart via

Chart via

Chart via

Chart via

Swinging strikes are great, enough said.. Fly balls are mostly good, provided that they're in the ballpark (and ideally pop ups). Batters whiffed on a third of their swings against Dayton's fastball last season. He also did a great job inducing pop flies (14.3% of batted balls), but also surrendered his fair share of long balls (14.3% HR/FB). In the podcast, Dayton noted that he made a conscious effort to keep the ball very high in the zone in order to generate whiffs and garner pop ups. Here's proof in the form of a pitch location heatmap:

Chart via Baseball Savant

Chart via Baseball Savant

Dayton also said that he claimed that his fastball was more likely to get crushed when down in the zone. Was he right? It appears so:

Chart via Fangraphs

Chart via Fangraphs

See all that red in the bottom of the zone? That's where opposing batters' isolated power marks were the highest against Dayton's fastball. Intuitively, that makes sense and should be fairly consistent with regard to high spin fastballs. The higher spin rate causes the fastball to drop less than usual during its trip to the plate, making it more likely for a batter to swing under the ball. Thus, there are more batted balls that are airborne against high spin rate pitchers. For a batter, it's physically more difficult to square up a fastball up in the zone that doesn't drop as much (or appears to rise) compared to a typical fastball, and thus, we should expect more whiffs and pop ups. On the other hand, when a ball is over the middle or low, the slower descent of a high RPM fastball can turn batted balls that typically would be grounders into line drives. It can also turn balls in play that normally would be liners into fly balls.

If I may compare this post to a supermarket's layout, there's a reason the milk is all the way in the back of the store. Just like how many shoppers go to a supermarket and need to get milk, I imagine most readers come to this blog to get Yankees content. But to get to the milk, shoppers need to browse the rest of the store's offerings first, giving the store more opportunity for profit. Unfortunately, there's no profit in this article, but I did feel like the Dayton angle was important to establish. Alright, alright. On to the Yankees. 

The Yankees have a handful of pitchers who possess above average spin rates on their fastballs, and I'm going to highlight a couple of them. One of the obvious players in said group is Aroldis Chapman, but I won't focus on him. We already know he's a great pitcher. I'm going to touch on a two of the unheralded hurlers that could take advantage of the spin on their heaters.

After Chapman, the Yankee with the highest average spin rate on his four-seamer last season was Ben Heller at 2,660 RPM. That's only 10 RPM behind Chapman, and judging by the charts from above, it's unquestionably elite. When you take into account Heller's 95.5 MPH average velocity on the offering, there's a chance for it to be a dominant pitch. If only he would throw it up in the zone more often...

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That might explain why Heller garnered only 11.3% whiffs per swing, whereas Dayton (and Chapman) did so on a third of all swings. Granted, Heller tossed merely 7 innings in pinstripes, so small sample size caveats apply. But I'd like to see him elevate the ball more in order to take advantage of his velocity and spin.

Next on the list: Chasen Shreve. You heard me right. Shreve average 2,608 RPM on his heater last season, but didn't take advantage of it. His 5.18 ERA and 2.18 HR/9 in 33 innings were unsightly, yet maybe he could rediscover some of the success he had back when he was first acquired prior to 2015. Half of Shreve's eight home runs allowed in 2016 were on the fastball, though his whiff/swing on the pitch was actually quite good (24.0%).

Based on location, Shreve might be able to limit the damage if he could bring his fastball into the upper third more often. As an additional benefit, it could improve his already solid ability to make batters feel the breeze.

After Chapman, Heller, and Shreve, the four-seam fastball spin rate leaders takes a bit of a drop. There are a few still above the average mark of 2,264, but not quite elite. Here's the list I pulled from Baseball Savant:

Screen Shot 2017-02-23 at 10.29.34 PM.png

A few guys that I was surprised to see below average with brief reasoning in parentheses: Andrew Miller (velocity), Jonathan Holder (gaudy minor league numbers), Luis Severino (velocity), Dellin Betances (velocity), and Michael Pineda (velocity). Obviously, based on my assumptions, velocity isn't everything. Dayton's spin rate should have taught me that. Low spin rate might explain some of Severino's and Pineda's struggles last season, but that's another post for another time.

One other quick observation: look how low Sabathia's RPM was! I'm kind of doubting it's accuracy, to be honest. There's always a chance for some misreadings in systems like Statcast, but there are 792 pitches to play with here so perhaps it is valid. With that in mind, referring back Petriello's article I linked before, Petriello noted that low spin rates aren't necessarily bad. Very low spin rates are associated with more grounders, and that sure sounds like Sabathia's game nowadays. Ground balls and weak contact led to much of his resurgence last season.

Ultimately, spin rate is only one aspect of pitcher evaluation. There are so many other things for a pitcher to worry about, especially because spin rate doesn't seem like something easily manipulated. Either you have a high spin rate, or you don't. That being said, it would behoove pitchers like Heller and Shreve to capitalize on their high-end RPM fastballs. Heller is seeking to establish himself as a key cog in the bullpen this year, while Shreve is running out of chances to prove himself worthy of a role in the majors. If they can elevate their fastballs more frequently, it wouldn't be surprising to see either of them put together strong campaigns this year.