The Rockies have signed right-hander Diego Castillo to a minor league contract, according to Aram Leighton of Just Baseball Media. The pact includes an invitation for Castillo (who turns 31 next month) to attend Colorado’s big league spring camp.
Castillo is best known for his five-year run as a workhorse in the Rays’ and Mariners’ bullpens from 2018-22, as the righty posted a 3.12 ERA, 28.1% strikeout rate, 50.7% grounder rate, and 8.9% walk rate over 259 2/3 innings and 250 appearances in that span. Unfortunately, he got off to a very rough start in his first eight games (and 8 2/3 innings) in 2023, leading the Mariners to outright him off their 40-man roster at the start of May. Castillo spent the remainder of the season at Triple-A, then elected free agency at season’s end.
The Rangers signed Castillo to a minor league deal last winter and released him near the end of Spring Training, with the Twins then quickly adding him on another minors contract. Castillo’s season in Minnesota saw him twice designated for assignment and outrighted off the 40-man roster, and he re-signed another minor league deal with the Twins after opting for free agency after that initial outright at midseason. All of this movement resulted in another season of pretty minimal MLB playing time, as Castillo appeared in 10 games with the Twins and posted a 2.70 ERA in 10 innings.
Control is the biggest issue behind Castillo’s decline, as his walk rate has shot up to 14.92% over 84 1/3 innings of Triple-A ball over the last two seasons, and 17.9% in his brief MLB sample size of 18 2/3 innings. A velocity drop may have also been partially responsible for Castillo’s struggles in 2023 specifically, though his fastball ticked upwards from 93.8mph in 2023 to 95.9 mph in 2024.
Castillo’s prime years are recent enough that it makes sense that teams would still want to take a flier on the veteran righty. For the Rockies in particular, his ability to keep the ball on the ground could be useful in the thin air of Coors Field, if Castillo can earn himself a shot on Colorado’s active roster.
