The Rockies have claimed right-handed Blas Castaño off waivers from the Mariners, according to announcements from both clubs. The righty had been designated for assignment by the Mariners a week ago. The Rockies have optioned him to Triple-A Albuquerque. In a corresponding move, left-hander Luis Peralta has been designated for assignment.
Castaño, 27, was originally an international signing of the Yankees out of the Dominican Republic. He was released in the summer of 2023 and scooped up by the Mariners. He impressed his new club in 2024, posting a 4.38 earned run average in 125 1/3 minor league innings, spending most of that in the hitter-friendly Pacific Coast League. He was added to the 40-man roster in November of 2024 to keep him from reaching minor league free agency.
He has spent the past year-plus as a depth arm for the Mariners without being needed much. He has only made one big league appearance, which was a three-inning relief outing in May of last year.
He tossed 126 2/3 innings for Triple-A Tacoma last year with a 5.19 ERA, in the unfriendly confines of the PCL. His 17.8% strikeout rate and 9.3% walk rate weren’t especially strong but he did induce grounders on 46% of balls in play. So far this year, he has been pitching out of the bullpen, throwing 6 1/3 innings over six appearances for the Rainiers. His 1.42 ERA in that small sample looks nice but his strikeout and ground ball rates are around the same level as last year.
The Mariners bumped him off their roster but the Rockies will take a shot on him. They may be attracted to his diverse pitch mix, something that has seemingly become an organizational preference. Statcast categorizes him as a five-pitch guy. He doesn’t throw his four-seamer often, leading instead with his sinker, in addition to a slider, cutter and changeup. His fastball and sinker average around 94 miles per hour, the cutter around 90, the changeup in the high-80s and the slider in the low-80s.
The Rockies could stretch him back out or keep in a relief role. They need pitching either way. They had a 5.99 ERA as a team last year, easily worst in the majors. They have a 4.40 mark so far this year, bumping them into them out of the bottom ten of MLB clubs, but in a much smaller number of games. Whether he’s working as a starter or a reliever, the Rockies can keep him at Triple-A until he’s needed. He can still be optioned for the remainder of this season and another season as well.
Peralta, 25, was acquired from the Pirates in the 2024 deadline deal which sent Jalen Beeks to Pittsburgh. Peralta, the younger brother of Freddy Peralta, showed some potential around the time of that trade but his stock has fallen.
Initially a starter, he was moved to a relief role by the Pirates. Between the Bucs and the Rockies, he tossed 47 2/3 minor league innings in 2024 with a 0.94 ERA. His 11.2% walk rate was high but he struck out 40.1% of opponents and induced grounders at a 48.8% clip. He also posted a 0.73 ERA in his first 12 1/3 big league innings.
2025 was a big step back, as he posted an ERA above 9.00 in both the majors and the minors. His 28% strikeout rate in Triple-A was still good but a big drop, while his walk rate climbed all the way up to 15.4%. In the majors, his 17.8% walk rate was worse than in the minors and also higher than his 15.8% strikeout rate, with both of those figures being well worse than average. So far this year, he has thrown 7 1/3 innings in Triple-A with a 31.1% strikeout rate but a 28.9% walk rate and 14 earned runs allowed.
Those struggles have nudged him off Colorado’s roster. DFA limbo can last as long as a week. The waiver process takes 48 hours, so the Rockies could take as long as five days to explore trade interest. His recent numbers are obviously not good but perhaps some clubs see a path to getting him back to the dominant form he showed in 2024. He still has options and could be sent to the minors if any club acquires him in the coming days.
Photo courtesy of Jayne Kamin-Oncea, Imagn Images
