How Diego Castillo Found His Mojo

Diego Castillo had a pretty solid debut once he got here. The bad news was, it took a little longer than Rays fans wanted. The good news was, it eventually got better than just “pretty solid.”

Signed as an International Free Agent in March 2014, Castillo rose steadily through the Rays system before breaking out in 2017. Splitting that season between Montgomery and Durham, the big Dominican righty paired his 3.27 ERA with 90 strikeouts against just 20 walks in 71+ innings. However, despite a strong spring, Castillo — like much of the Tampa Bay youth movement — would have to wait a little longer before he could show fans at the Trop what was rumored to be a 100 mph heater and a plus-plus slider. In the meantime, Castillo went about his business of dominating minor league hitters.

The call finally came in June, when Chris Archer hit the DL. Castillo was called up, making his debut on June 6 against Washington in an otherwise unremarkable blowout loss.

Just don’t tell Brian Goodwin it was unremarkable.

Or Trea Turner, for that matter.

Castillo continued to pitch well through June, posting an ERA under two in 10 games. He was used often for more than an inning, and almost never in back to back games. It was a good, comfortable role for the rookie.

Struggles came in July, mostly due to a rising BABIP and an uncharacteristic walk problem. But what was more concerning was that Castillo still wasn’t quite showing the velocity we were promised from either his fastball or his slider. Not during the fast start in June, and certainly not during the rocky July. If anything, it looked like things were trending the wrong direction.

Castillo’s results rebounded as the calendar turned to August, and the velocity seemed to be bouncing back a bit as well. It still wasn’t really the 100 mph gas we had heard scouts rave about, but the stuff was still pretty filthy when he was on. Sure, maybe he wouldn’t be must-see-Diego, but you could see yourself being comfortable when Castillo came into a game for years to come.

But then, rather unexpectedly, something clicked.

It started when Kevin Cash tabbed Castillo to Open on August 24 against the Red Sox. A scoreless, five-out performance followed, so Cash called on him again on August 29. And then he called on him again. He kept calling on Castillo, not just because it was working, but because Castillo looked electric doing it.

Via Brooks Baseball

I’m not a baseball scientist, but do you see the way that line is going up? That’s generally bad news for hitters.

But maybe you aren’t a chart person. Well then, how about this?

Hey, don’t laugh. You try and hit that when you’re looking for 101.

Of Castillo’s last 14 appearances, he opened in 11 of them. During those opens, his fastball averaged nearly 100 mph in the first inning, and over 99 mph when he came back out for the second. Additionally, his slider picked up some gas as well, coming in at 90/91 in the first two innings instead of the 88/89 we had become accustomed to. Whether by accident or shrewd coaching, it seemed like the Rays had unlocked Castillo as a big leaguer.

Not that you’d know it from talking to him. Our own Carl Gonzalez sat down with Castillo last September. This, apparently, is the secret sauce:

“I don’t really worry about my velocity. I really just worry about the basics. Make sure they don’t hit it. I honestly just go out there, speed it up my arm and let it go with purpose behind it.”

Welp. There ya go. Speed, purpose, “don’t hit it,” whatever, but something clicked for the rookie, and Rays fans hope it keeps clicking.

What’s Next?

What can we expect out of the big fella this year? Hopefully more of the same. With two Opener slots to fill in the rotation, we can expect Castillo to be on the short list. We can expect him to work some relief outings in between opens. We can probably expect him to keep getting days off between outings.

Most of all, if everything stays clicked, we can expect some very sad hitters.