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Diego Castillo is the Rays future closer

This young talent shouldn’t be ignored

MLB: Toronto Blue Jays at Tampa Bay Rays Kim Klement-USA TODAY Sports

Among the many names you could follow in the Rays rebuild, Diego Castillo has been one of the best talents the Rays have called upon this season.

It seemed to be a matter of when-not-if Castillo would be called up in 2018 after a strong 2017 and dominant showing to begin the year.

Castillo has the stuff you’d like to see in a back-end reliever. He has a plus fastball that touches 99 and moves all over the place, quite naturally too. The slider can run up to 87, and he offers different variations of it. It plays more like a cutter at times, but there are moments when it plays like a traditional slider. He’s been prone to random command lapses throughout his minor league career, and while it’s shown up in the big leagues as well, the stuff is good enough to help him through those rough stretches.


Castillo has a fastball that he isn’t afraid to throw, and he shouldn’t be. It moves inward, outward, downward. Statcast doesn’t even know how to pick it up. It calls it a sinker most of the time, but we know it’s really just his fastball.

Brooks Baseball picks up -7.89 inches of horizontal movement on the hardball, and a negative number on a righty means he’s prone to getting arm-side run on the pitch.

Exhibit A:

That one looked like it had heavy sink on it because of how Ramos caught it, but it’s just a prime example of how much run Castillo is able to get. However, with the small sample we’re afforded at this point, we know the fastball has been getting touched up a bit.

Opposing hitters are batting .286 against it, but for those that don’t really care about BA he’s holding the competition to a .292 wOBA. At the end of the day, a fastball with natural arm-side run and the ability to throw it for strikes should allow Castillo to continue working off his slider.

Slider (or Cutter if you’re Statcast)

His bread and butter.

Yes, it’s a slider.

Statcast only just recently decided to pick it up as a slider, and there’s a reason to that. Castillo is able to throw different variations of it, and it must confuse Statcast to the point where it wants to call it a cutter.

Touching on the variations of sliders that Castillo can throw, it comes as no surprise that he’s able to put nearly 2400 RPM’s of spin on it. Hitters have also put up a .154 wOBA against the slider/cutter hybrid.

The slider above has less break on it. Castillo threw it harder, and it lost some of its movement. It’s easy to see why Statcast can get crossed up. The classifications aren’t done by hand, after all.

With this much variation on a talented slider, it might be the best such pitch on the entire pitching staff.

Diego Castillo should be a big part of the Tampa Bay Rays for the foreseeable future. If you think he’s the closer of the future, you’re probably right. The Rays do things differently though, and his role could change on a day-to-day basis.

Regardless, he’s a power arm with the ability to do special things and if his command remains the same with the occasional spottiness, he could still find his place among the best relief arms in the game. I don’t think that’s too far fetched.