Aroldis Chapman’s Debut is a Window into His Future

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The Yankee bullpen has been exceptional in the early going of the season, surrendering just 7 hits, 3 walks, and 1 earned run in its first 18.2 innings of work. While it has been a collective effort, the most encouraging development came last night’s during Aroldis Chapman’s disgusting debut. The Yankee closer threw 19 pitches and generated 10 swings. Of those, 7 (!) came up empty. He was filthy – and, reading between the lines, there are clear signs Chapman will be as effective as ever.

That should not be a surprise to anyone, two backbreaking postseason home runs aside. The lefty closer has been the most important and dominant piece of the Yankee pen since he joined the team. For context, there are 236 qualified relievers in baseball from 2016 through last night’s games. Here are Chapman’s rankings among them in a few key categories:

  • FIP: 2.12 (1st)
  • fWAR: 8.5 (2nd behind Kenley Jansen at 8.6)
  • Average FB Velocity: 99.7 miles-per-hour (2nd behind Jordan Hicks)
  • ERA: 2.36 (2nd behind teammate Zack Britton)
  • ERA-: 54 (2nd behind teammate Zack Britton)
  • Strikeout Rate: 38.9% (5th)
  • Strikeout-to-Walk Rate: 28.4% (T-5th)
  • BAA: .168 (5th)
  • WPA: 8.25 (8th)
  • WHIP: 1.02 (13th)

I put such a long list there because I think it is worth re-iterating in the strongest possible terms that Chapman has been an exceptional reliever with New York – and, if last night is any indication, that is not going to change any time soon. That is actually fairly remarkable from a baseball perspective.

Chapman has lost two-to-three full miles-per-hour off of his fastball since joining the Yankees in 2016, when he averaged more than 100 miles-per-hour on the offering:

Now, it is certainly true that Chapman is still throwing 98, on average, and that he can still dial it up to triple digits. But it does mean that his days with an everyday strategy relying on “here is a 102 miles-per-hour fastball down the dead of the zone, I dare you to hit it” are mostly behind him. That velocity was a differentiator for the lefty. His current velocity is still fast, but much more commonplace. Not many pitchers can do this, for instance (from May 2016):

The point of this is to say that Chapman has been forced to change up his pitching style to compensate. He can’t really just rely on throwing it hard as hell and straight as hell any more, at least not as consistently as he once did. The good news is that he’s not.

Back in 2019, when Chapman threw just fewer than 60% fastballs for the first time in his career, I wrote about the addition of his new slider. The pitch was effective and helped keep Chapman at the top of his game. Last year, he made another addition: a splitter he threw 6 times across the regular season and playoffs. As Derek noted last year, the pitch was nasty, with an extremely low spin rate (good for splitters) and a ton of movement. It looked like this:

The only catch was that Chapman threw just 6 of them. That does not make a sample size, nor does it really indicate that the pitch was here to stay. That started to change this spring, though. Chapman threw the pitch 10% of the time in March, telling us at least that he was serious about trying to make it work. Players tinker all the time without it sticking, but it was at least indicative of the fact Chapman likes the splitter. We saw more signs last night that he does indeed like the pitch.

It took Chapman 19 pitches to strike out the side against Baltimore, but the Spring Training ratio held. He threw 2 splitters (or 11% of his pitches), the Orioles swung twice, and they whiffed twice. Here was the first one:

And here was the second one:

Note that both came with two strikes, too: Chapman is clearly using it as a put-away pitch. The second one is a pretty clear indication why. Where the first pitch has a lot more movement – it is a bit loopier – the second one is straight…right until it is not. That is going to be a really tough pitch for any hitter to square up or even lay off. It really plays off his world-class fastball and its reputation. The addition of the splitter, coupled with a very effective slider, can help extend Chapman’s lifespan as one of baseball’s best relievers.

Now, I’m not quite ready to declare that Chapman’s split finger has capital-A Arrived. (I’m only 95% there.) What I am ready to say is that this is another extremely encouraging development from one of the best relievers in baseball. Relievers are fickle and many cannot handle even losing a hair off their fastball. Chapman, when he added his slider, showed that he is capable of flexibility and adaptation. His new toy is another indication that he won’t just tinker, but that he’ll tinker successfully.

For the Yankees, who will call Chapman closer through at least 2022, that is a very good sign indeed. Locking down the 9th inning with Chapman allows Aaron Boone the flexibility he needs to use the many other dominant relievers on the team as firemen. If Chapman’s debut is any indication, then that formula is not going to change any time soon.


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  1. MikeD

    The days of peak 105 mph Chapman are gone, but he can still hit 100-102 with regularity, which means he remains in an elite class, especially as a lefty. Frankly, he could decline to mid-90s through his 30s, and the addition of his nasty splitter could very well carry him through until he’s 40. Lefties with gas, even declining gas, can still be very good with a good breaking pitch. He has two with the slider.

    Has any pitcher gone from a reliever in his 20s to a starter in his 30s?! It always the other way around. Not being serious, but a lefty with high-90s heat with a good slider and an excellent splitter is a starter’s arsenal.

    • SteveW

      Charlie Hough was primarily a reliever until age 34, when he converted to starting. (He started 417 games after converting.) Of course, he was a knuckleballer, so he perhaps deserves an asterisk.

  2. SteveW

    I’m no fan of Chapman’s, but I do respect that he is proactively trying to stay ahead of the curve, rather than waiting until his performance starts declining.

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