Aroldis Chapman Is Struggling With the Where and How

One of the best closers in the game is struggling. In fact, one of the best closers in the game isn’t even being used as a closer at the moment. Last week, Yankees manager Joe Girardi effectively demoted Aroldis Chapman from his end-of-game duties, stating that he would use the hard-throwing left-hander “at any point.” This followed a series of shaky outings during which Chapman conceded seven runs in 4.1 innings.

Though he possesses a strikeout rate that would still make most of the league jealous, it’s also the worst of his career. And while he’s also experienced some misfortune on balls in play, there’s a sense that the misfortune is “earned.” And it is, in a way. It’s a little bit about how he’s throwing the ball, but also a lot about where.

Chapman’s velocity looks the same as it’s ever been, but that doesn’t mean that his fastball is the same. The spin rate on his four-seamer is down to one of its lowest points since we’ve tracked this sort of thing.

He’s basically gone from averaging 2600 rpm to, recently, around 2400. Look at this great chart by Jonah Pemstein from his piece on the effect of spin on outcomes, and you can see that 200 rpm on the four-seam — especially the 200 from 2600 to 2400 — is important.

Chapman is averaging 100 mph on the fastball right now, but that doesn’t necessarily mean the fastball is in ideal shape. In related news, Chapman has only recorded one month — September of 2012 — during which the swinging strike rate on his fastball was worse than it has been so far this August. July and August now represent the worst two-month stretch of his career, unless you count April and May 2011, which happened right before he went on the disabled list.

Not only is the spin down on the fastball, making it more hittable, but the effect is exacerbated by Chapman’s tendency to throw the ball to locations that make this contact more difficult to manage.

Here’s the theory: there are spots in the zone that lead to higher exit velocity. We can figure out the expected exit velocity based on zone location, and then judge how often a pitcher throws to those spots. It basically allows us to divorce process from results: how often does the pitcher throw to the bad parts of the zone?

Turns out, Chapman does this more often than almost anyone, and it’s gotten even worse this year. Since 2015, Chapman’s expected exit velocity based on location is fourth worst among those with at least 200 pitches. Here’s the leaderboard for this year:

One thing that may surprise you is the general quality of the pitchers on this list. I will submit to you that there’s something this entire group has in common: big fastballs and not much command. As a group, they throw to places that normally produce high exit velo, but as a group, they don’t produce that same exit velocity because they have big fastballs.

But we know something about Chapman’s fastball right now: it’s not playing as big as it used to. So when you see how the league does based on location (left) and then see where Chapman is throwing his pitches right now (right), you might get a little nervous.

Chapman might still be fine. He’s throwing 100. That’s a good first step. But what we are seeing now could also be a preview of the decline phase of his career. When a pitcher who relies on spin and velocity doesn’t have that same spin and velocity, he has to place it better in the strike zone. That may not be a skill at which this particular pitcher excels.

Thanks to Andrew Perpetua for the data and images.

Update from Perpetua: Check out where the drop in swinging strike rate when you fall from 100 mph / 2600 spin rate on the following chart: