Aroldis Chapman's fastball is no longer special
Not long ago, Aroldis Chapman's fastball demolished all conceptions of how hard a human being can throw a baseball. When 100 mph was almost unheard of, he touched 105 mph. Statcast had a search filter for velocity specifically to remove him because he clogged up the leaderboards too much; you couldn't see any other pitcher. He overwhelmed and overpowered opponents with pure, unprecedented heat.
Fast forward to the present, where he surrendered the go-ahead run in Saturday's 4-3 loss to the Baltimore Orioles on a sacrifice fly, letting the Tampa Bay Rays further distance themselves in the AL East standings. As with all sac flies, the real story is the lead-up. After Ryan Mountcastle reached on a wild third strike, Chapman threw his legendary fastball for ten of the next 13 pitches. Seven of the ten missed the strike zone, including a pair of bouncers in the dirt. After falling behind Austin Hays 3-0, he pumped one in for a strike... at 95.7 mph.
Not So Fastball
Pure velocity means little without command, which he clearly lacked on Saturday. However, even when he locates successfully, his heater simply isn't what it used to be. If he threw a pitch less than 96 mph when he first joined the Yankees in 2016, it would've been more likely to be some kind of offspeed or breaking pitch. He didn't throw any fastballs that year at 95.7 mph or lower, though he did hit 94 mph with a slider.
Here's his average four-seam fastball velocity by year:
His average fastball was 101 mph in 2016. Now it's 98.6 mph, though he did regain half a tick from his nadir in 2019 and 2020. He's 33 years old now, and no one can throw that hard forever, but he's reached the point where his fastball no longer packs the same old sizzle on a consistent basis. He can still touch triple digits, but not as frequently as he used to do. In 2016, 57.8 percent of his fastballs were at least 100 mph, which was easily the highest percentage in MLB. This year, it's 15.8 percent, sixth-best in MLB. From 2010-2018, he eclipsed 103 mph 270 times while every other pitcher in MLB combined did it only 70 times. Since 2019, he's only reached 103 twice.
Catching Up
The problem with pushing the upper limits of the human body is that once something is possible, other people start to do it too. Since 2019, 81 pitchers have touched triple digits. Chapman's fastball used to stand alone on the velocity mountaintop, but now he's just part of the crowd.
His average fastball velocity this season is 99th percentile, which is still excellent, but there's a big difference between 99th percentile and 100th. He no longer throws so hard that the opposing hitter will have never seen that type of velocity before. Indeed, fastball velocity around MLB has increased dramatically. Here's the average MLB fastball velo by year:
2016: 92.3 mph
2017: 92.8 mph
2018: 92.8 mph
2019: 93.1 mph
2020: 93.1 mph
2021: 93.5 mph
A 1.2 mph league-average increase over six years is enormous. While most of the league still can't catch up with Chapman's fastball at its best, just about everyone is better than his worst. Even though he tops 100 frequently this year, when he doesn't have his best heater it's not much faster than average. He's thrown 39 fastballs under 96 mph this season. Here's one he threw only 93.8 mph on July 6:
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Even though it was well located, that's a very hittable pitch, and Seattle Mariners infielder Ty France poked it into right field for a single. Just like every other MLB hitter, he sees 93.8 mph fastballs every day. 637 pitchers have thrown at least one pitch 94 mph or better in 2021.
In his heyday, Champan's fastball overpowered hitters nearly all the time. He's still capable of reaching back for that elite heat from time to time, but more often than not, he sits in the high-90s with a few in the mid-90s. 186 pitchers hit 98 mph this year, which is right about where Chapman averages.
Hitting Spots
Let's revisit Saturday once more when Chapman loaded the bases with no outs in the ninth inning of a tie game. Things went off the rails when he allowed a single to Austin Hays and walked Trey Mancini. There were a few fastballs in that two-batter sequence with mediocre velocity, but that wasn't the main problem. In fact, he hit 100 mph on the 1-1 pitch to Mancini.
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This was the fastest pitch thrown by any pitcher on either team during the game. The problem was that he desperately needed a strike to get ahead of the count with runners on first and second with no outs, but the pitch was low by about six inches.
Chapman's fastball no longer pops 100 mph as effortlessly as it used to. As a result, he hasn't located well when reaching back for max velocity. Since July 28, ten of the 16 100 mph pitches he's thrown have been balls. This is a big reason why he's walked 32 batters in 45 innings. His 16.4 percent walk rate is his worst since 2011, which was his first full season in MLB.
Failing to throw strikes has other consequences too. Facing Hays, he fell behind 3-0 on three straight fastballs out of the zone. After a called strike on his lowest velocity fastball of the outing, he hung a slider which was deposited into left field for a single. Had he not fallen behind in the count, he would have most likely thrown a less hittable pitch.
Even with an outstanding 39.3 percent strikeout rate and 15.2 K/9, this has been the worst season of Chapman's career so far. He has allowed more hits, walks, and home runs than usual. His once trusty fastball is no longer the marvel it used to be, and when he fails to throw it for strikes, it's the culprit of his downfall.