The Other Thing about Aroldis Chapman

I understand the lot of you are preoccupied with thinking about the imminent trade deadline. I understand some might think I write about Aroldis Chapman too much. But Chapman is maybe the funnest pitcher in baseball, so I wanted to take a moment to share a fun fact that has to do with what people don’t talk about when they talk about Chapman and his unparalleled skills. You can go right back to thinking about the deadline in a few.

The Chapman story, of course, is about his fastball, of course. People who hardly know anything about baseball know that Chapman throws the baseball faster than anybody else. It’s the kind of fact that appeals to both die-hards and casual come-and-go sorts, and the heater makes every Chapman appearance a spectacle. After every pitch he throws, all eyes in the ballpark turn toward the radar-gun display. There’s injury concern when Chapman throws a heater slower than his body temperature. Chapman is crazy specifically because people can’t imagine squaring up a fastball at 100+ miles per hour. You think of Chapman and you think of whiffs, because the fastball seems downright unhittable.

It’s basically unhittable, yeah. It’s unhittable in the way that 2014 Clayton Kershaw is perfect — it’s not literally true, but it’s about as close to true as it’s going to get for any human. Here’s a familiar sight: Chapman blowing heaters by major-league hitters.

Chapman’s contact rate this year is stupid. His strikeout rate this year is stupid. His strikeout rate is closer to 60% than 40%. His strikeout rate is closer to 80% than the overall reliever league-average. Yes, it’s hard to hit his fastball. It’s also hard to hit his slider, when he throws it, and he’s occasionally mixed in a mean-spirited changeup, too. But check out some other swings Chapman has generated just this week, against the same opponent featured above:

Well that makes sense, right? Chapman’s fastball is hard to hit, so it’s also hard to hit fair. Everybody understands that, against Chapman, hitters swing and miss a lot. What no one really talks about is that, also, against Chapman, hitters swing and hit the ball foul a lot. Foul balls are strikes. Foul balls are good for the pitcher, especially when he possesses putaway stuff.

Against Chapman this season, about 42% of all swing attempts have whiffed. The league average is roughly 21%. Against Chapman this season, about 70% of all balls struck have been hit foul. The league average is roughly 48%. The lack of contact is absolutely nothing new. Turns out, the same goes for the quantity of foul balls. Let’s examine Chapman’s career, playing with z-scores, or number of standard deviations away from the average.

Remember that, assuming a normal distribution, greater than 99% of everything should fall within +/- three standard deviations of the mean. Certain baseball stats aren’t quite normally distributed, but they’re close enough for the assumption to not be misleading. Here’s a plot of Chapman’s whiffs over swings, and fouls over contacts:

In 2011, Chapman’s whiff rate was 2.6 standard deviations higher than the average. This year that’s all the way up to 4.1. Meanwhile, his foul rate has been extremely high, too, the whole entire time. This year it’s also up to 4.1. It’s excellent to be three standard deviations better than the average. Four is insane. 2014 Aroldis Chapman, it follows, is insane. He almost can’t be hit, and when he is hit, he almost can’t be hit fair.

Chapman isn’t the only guy with obscene whiff rates and foul rates. Here’s a table of six foul-happy names, covering the window of 2011 – 2014:

Pitcher	Foul/contact%	Whiff/swing%
Aroldis Chapman	64%	39%
Craig Kimbrel	61%	38%
Kenley Jansen	62%	34%
Ernesto Frieri	62%	30%
Jake McGee	62%	26%
Jason Grilli	60%	29%

It should be obvious that these numbers are closely related to high and high-velocity fastballs. In that regard all these pitchers are similar, so Chapman isn’t totally off by himself, but he still has the highest foul rate of the group, and the highest whiff rate. And his numbers in 2014 are better than ever, as he’s just not even giving opponents a chance. Presumably, this has something to do with the fact that Chapman’s average fastball velocity is the highest it’s ever been.

You might be curious about 100+ mile-per-hour fastballs, isolated. Here’s a Chapman-specific table:

Stat	2011-2014	2014
Foul/contact%	70%	72%
Whiff/swing%	41%	45%
In Play/swing%	18%	15%

Those pitches are both harder to hit, and harder to hit in play, as I’m sure we all assumed. Not that Chapman hasn’t done good work with both of his other pitches, but in part because of those other pitches, his fastest fastballs have gone by almost unhurt. He has allowed runs before, but I don’t think anyone’s worried about them. His FIP right now is 0.49.

Obviously, Aroldis Chapman gets a lot of swings and misses. Less obviously, but intuitively, he also gets a lot of swings and foul balls. The end result: against Aroldis Chapman, it’s almost impossible to swing and put the ball in play. On average, about 40% of all swings strike the baseball and hit it fair. Here’s Chapman, year by year:

2011: 24% in-play rate
2012: 22%
2013: 22%
2014: 17%

His in-play rate right now is genuinely less than half of the major-league average. Chapman, for his career, has allowed 14 home runs. He’s yielded a .272 BABIP. There are rewards there, that in theory are accessible for any major-league hitter. But they’re surrounded by an almost impenetrable field of lasers and land mines, as it turns out having less time to react means hitters are less likely to both make contact and make worthwhile contact. It’s no secret why Aroldis Chapman succeeds. But it’s ever so fun to break down the How.