Sunday night, Rafael Devers went yard against Aroldis Chapman, even though Chapman’s fastball was recorded at nearly 103 miles per hour. It’s the fastest pitch hit out in the pitch-tracking era, which has spanned nearly a decade, and that linked article was almost obligatory. Had to write something up. Devers tagged Chapman, even though it seemed like Chapman had his best stuff.

To a certain extent, you can’t blame Chapman for what happened. He threw a lefty-on-lefty fastball, with two strikes, kind of up and in at over 100 miles per hour. That pitch should basically never go for a homer. I’m still not sure how it happened. But, ignore the homer for a moment. Pretend it was a double, or a single. Or even an out! Whatever you like. Devers made contact. Solid contact, at that. The contact is what’s strange, and there are signs of a problematic trend, here.

Let’s examine Chapman’s career, shall we? I’ve prepared three rolling-average plots, each using samples of 30 games. This first one shows the development of Chapman’s average fastball.

You could argue there’s a recent down tick, but Chapman is still regularly reaching triple digits. His fastball is fast. Still a Chapman fastball. Like we all saw with the at-bat against Devers, Chapman can still run it up there about as hard as he ever has. So, based on the velocity, Chapman seems okay. Shifting to pitch location, we can see a trend from the past year and a half or so.

Chapman has been aggressive with pitching in the zone. He’s thrown two-thirds of his pitches for strikes, and this year in particular, he’s regularly gotten ahead with the first pitches of plate appearances. And, of course, with such an unhittable fastball, why mess around? Chapman had a terrific 2016, in which he came right after his opponents. This year, he’s done much of the same. But-

That plot shows contact rate. Chapman’s present contact rate is far higher than it’s been since earlier in 2013. All of a sudden — it’s not so much that Chapman is hittable, but he’s a great deal more hittable than he’s been. Look at this table of the biggest contact-rate declines from last year, with a minimum of 30 innings:

Chapman has a contact rate of 75.2%. The league-average reliever has a contact rate of 75.4%. No pitcher’s contact rate has dropped by more, and although Chapman is still mostly okay, and although this could be a blip, he was on the disabled list for a month, with a rotator-cuff problem. His contact rate has only risen since he came back. The velocity is there, and maybe that’s the most important thing, but you do have to wonder. Chapman’s been one of the most dominant relievers anyone’s ever seen. Real cracks appear to be forming.

Related to this, consider Chapman’s year-to-year ranks among all relievers in Win Probability Added:

2011: 24th

24th 2012: 8th

8th 2013: 44th

44th 2014: 15th

15th 2015: 16th

16th 2016: 7th

7th 2017: 337th

I don’t know what the issue is. It wouldn’t be a surprise at all if it were linked to the injury. In that case, it would be nice to have an explanation. But even then, explanation isn’t resolution. Aroldis Chapman is allowing roughly league-average contact. He’s in the first year of the largest contract a reliever has ever signed.