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Diego Castillo throws the ball hard

DRB spoke to the Rays rookie about his approach

MLB: Tampa Bay Rays at Atlanta Braves Dale Zanine-USA TODAY Sports

Since his call-up earlier this year, Diego Castillo has shown himself to be an intriguing talent. A few post-break struggles aside, he’s been a dominant piece in a dominant bullpen who is showing he can be trusted in multiple roles.

Can he open? Yep. Can he pitch in the 8th? Yep. Can he do it with 100 mph heat? You betcha... wait, what?

Castillo ran into trouble when his walk rate ballooned in July, when he allowed 9 free passes over 11.2 IP. He turned things around in August, however; he limited his walks to only 3 in 15 IP. We usually assume some trade off between velocity and command, but Castillo has improved his command while actually throwing harder overall.

It’s easy to forget that when the rookie Castillo debuted in June he wasn’t flashing triple digits on the radar gun.

Indeed, the average velocity on his hard stuff has crept up from 97.1 MPH in July to 98.22 in August. And for what it’s worth, the average velocity on the fastball is up to 99.43 here in September.

The sample for September is obviously a very small one, but the rise in velocity that began in August is very encouraging, and specifically, his plus-plus slider (which can be manipulated to have cutter movement) has also picked up nearly 2 MPH in the last two months.

What is going on with Diego Castillo?

I was able to ask him over the weekend.


Diego Castillo has only thrown back to back days once this year. The Rays typically use Diego after a few days of rest, and they typically use him to get more than 3 outs. 14 of his outings this year have gone further than 1 IP.

Now this might be a coincidence or maybe a shift in his mentality on the mound, but the gradual rise in velocity has come mainly after he began to open games in mid-August.

Castillo mentioned, “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.”

So again, it doesn’t sound like there’s much going on here behind the fact that Diego really is just....pitching.

So has Castillo found a sense of comfort in opening ballgames?

“In a way, I feel good,” Castillo told me, “Sometimes it’s tough, because I’m starting a game and especially in the big leagues since it’s not easy starting up here.”

Upon reflection, Castillo also referenced the familiarity that he and Kyle Snyder both share, and noted that their shared understanding of his capabilities helped the Rays to know when Castillo could handle opening duties.

And that’s it.

The Rays are putting him in a position to succeed, and Castillo is doing it. It really seems like he’s just going out there and letting it rip like he always does.

There are no obvious mechanical changes (like all pitchers, his release point has moved around a bit, but it’s splitting hairs to dig deep because there’s just nothing there). He’s just throwing the ball harder.

It’s also weird because Castillo is approaching the 72 innings that he hit last year between AA and AAA, which represents the highest inning amount of his career in a year. You typically see pitchers lose velocity at this time of the year, not gain it.

Credit has to be given to the Rays for deploying Castillo’s talents well, and kudo to Castillo for making the most of this opportunity.

Note: the interview was carried out in Spanish and translated by the author.