The Padres reliever that is striking out everybody

A few weeks ago, most baseball fans probably didn’t recognize the name Jose Castillo. A lot probably still don’t. To cut it short and get to the reason why he’s worth writing about is he’s faced 14 batters in his short major league career, striking out nine of them and walking none. Writing about a four inning sample size may seem dumb, but his start does have plenty of historical significance.

I took every rookie in the history of baseball with at least four innings pitched and ranked them by K-BB%. Castillo ranked first out of a 5,383 sample size.

To understand Castillo a bit more, let’s learn about his history. A 22-year-old that hails from Valencia, Venezuela, he was signed by the Rays in 2012. After seeing limited time as a starter and a reliever in the lower minors with mixed results. He was then shipped with Wil Myers and Ryan Hanigan to the Padres in 2014, a deal that brought the Rays most notably Jake Bauers. In his first year with the Padres organization, they worked him as a starter between two levels. He put up a 3.74 ERA in 79.1 innings, but limited the excitement by owning a 5.8 K/9 and 3.6 BB/9. The Padres didn’t like the ceiling for him as a starter, so he was sent to the bullpen, where he’s remained for the past three seasons.

Moving to the bullpen significantly upped the outlook for Castillo, as his profile as a pitcher has extremely changed.

Jumping to a more recent view, he’s been dominant at every level he’s played this year. In 15 innings at Double-A this year, he posted a 3.00 ERA and 1.76 FIP, striking out over 15 batters per nine. That was more than enough to get him a promotion to Triple-A, where he posted a 1.08 ERA and 3.56 FIP in 8.1 innings, striking out over nine batters per nine.

And it isn’t just the early results that are exciting for Castillo. He’s described as having a lively repertoire and a lefty possessing movement on both his fastball and slider.

“Jose Castillo snuck up on me a little bit as 2017 wore on; saw him a few times early in the year and put him in the back of my mind before really bearing down on him late in the year when he more consistently started flirting with an upper-90s fastball. The San Diego Padres protected him on their 40-man roster over the winter, indicating they’re clearly interested in figuring out if he can help the big league bullpen fairly soon; feels like there’s a natural fit here as a situational left-handed reliever with perhaps a chance at more general high-leverage set-up work assuming better command and consistency. Big-bodied kid with some baby fat still on him; naturally strong just by virtue of his build, but not necessarily well conditioned at this point; perhaps some modest room to add strength here in subtle ways that could help him consistently work in the upper 90s. Just turned 22 years old two weeks ago, so well ahead of schedule now with clearly some room left to grow into his body, as well as his career path.”

The pitch usage in these four innings has been a bit interesting. He only throws a fastball and a slider, actually throwing the slider more than the fastball. Out of 434 pitchers this year that throw a slider, there’s only 29 pitchers that do that, so it is somewhat rare. Castillo’s usage differential (slider% subtracted from fastball%) is the 20th lowest out of that same exact group.

The pitch that seems to be doing most of the work for him is the slider. On the 18 he’s thrown this year, nine have been whiffs. That 50% rate is tops in baseball.

The movement he gets on it is decent.

Baseball Savant

It is a small sample size and all, but the Padres have themselves a reliever that is showing insane results, has shown plus-control skills, has a fastball that sits mid-to-upper 90s, and a slider that nobody is picking up on.

It’ll be impossible for Castillo to keep up this K-rate, but he may just have had a better first four innings to a major league career than any pitcher ever has.

*All numbers and graphs are as of June 14th