The curious case of Cody Allen’s grounder year

Cleveland Indians closer Cody Allen is a very good, if pretty conventional, relief pitcher. He throws a curveball instead of a slider, but generally his profile is familiar. He get a lot of strikeouts. He gives fans a heart attack every now and again. And his batted ball profile has a stark outlier in it.

Usually a pitcher gains the reputation of being a groundball or fly ball pitcher. The second is also often tied to being a high strikeout guy, though nothing is permanent in baseball. Over the last three years, though, Allen has shown a very strange fluctuation in his batted ball profile.

One year is rarely enough to pull a concrete analysis from a relief pitcher. They just don't throw enough. Hence the inherent fickleness in the world of relief, and the unicornness of Mariano Rivera. In his career, Allen has generally been a fly ball guy with a 43.1 percent fly-ball rate. But the last three years have shown strange movement in that respect:

It’s great he’s comfortably negated line drives the last two years. But out of nowhere, he became a ground ball pitcher for a year, then reverted. At the time I, and surely most people, assumed Allen was taking advantage of a spectacular infield defense behind him, and making sure that home runs wouldn't be a thing for him at all. Of course, his home run rate per fly ball rate was a career-high 15.6 percent, nearly double his career rate of 8.5 percent. He was allowing less fly balls though, so there was more chance for a single dinger to influence the HR/FB rate. In all, it was one of his best years, including as sterling a playoff run as a relief pitcher could hope for.

Allen did not stick to this new version of himself, though. His home run rate has fallen back down to 8.6 percent, which is good news, but what happened with all the ground balls? You’d think he would have stuck with it, considering the success. Generally, grounders are good because they have a stunningly hard, probably impossible except in some magical moment, time becoming a home run, or even an extra base hit. That said, they can be major trouble in high leverage situations. While they can't do major damage, they can allow baserunners through seeing-eye singles and the like. That can lead to a snowballing inning that weak fly balls and decent outfield defense can stop. There is far too much luck involved in grounders. A lot of Bryan Shaw's problems have been because of squibbers that find a hole. Theoretically if a pitcher gets a ground ball, they've done their job usually. It just looks bad when the batter ends up a baserunner.

But where did the grounders go? How, if at all, has Allen changed? In rooting around some, I think it's due to his fastball. His curveball location has been markedly consistent - here is a gif of the last three years:

It is very hard to tell what is what because they're all going basically the same place. For the fastball though, it's a bit different. No GIF this time, sorry. More study might be needed since it’s a fine adjustment.

Here’s 2015’s fastball location:

Now 2016:

And finally 2017:

It seems as though there was a decided migration down in the zone with his fastball in 2016, though only an incremental amount from where he was in 2015. This year though, he's really hammering on that high cheese. He’s nearly abandoned the lower third of the zone. It makes some sense — his fastball's 2,505 RPM spin rate is about 300 revolutions above league average, which makes it seems as though it "rises" because it doesn’t drop quite as much as a hitter would expect it to, so hitters will be tempted to think a fastball just below the letters is a bit lower and swing and miss or pop out. Paired with his excellent curve, it's a perfect blend of high/low that will work time and again. It does lend itself to a flyball-heavy approach. Which he’s had, except for his 2016 gap year.

My only other question is whether this is on purpose. Only Allen, his catchers and his pitching coach know. There has been some slight shifting in his release point this year compared to the last two:

It’s not stark, though he is a bit lower in his release. The first image in the cycle also takes into account his flyball-heavy 2015 as well as last year. There’s been refinement there, which is a good thing. It means he’s more comfortable than ever with his curve, which is comparatively easy to lose the release point on. The infield is still very great, especially with the Urshela/Lindor/Ramirez setup that comes out late in games. Maybe it would be ideal for him to be more of a ground ball heavy pitcher with Bradley Zimmer gone for the year now. Its hard to trust the rest of the outfield quite as much. It was a weird blip, and Allen is back to his old ways. Most likely that’s all it is. But it was a strange departure.