The Rockies have made a strategic move in the off-season, acquiring right-handed pitcher Blas Castaño from the Mariners and designating left-hander Luis Peralta for assignment. This decision comes as the Rockies look to bolster their pitching staff and address their poor team ERA of 5.99 last year, the worst in the majors. The team's current ERA of 4.40 this season places them in the bottom ten of MLB clubs, but with a smaller number of games played.
Castaño, 27, is an intriguing addition to the Rockies' roster. He was originally signed by the Yankees as an international free agent from the Dominican Republic. After being released in the summer of 2023, he was quickly signed by the Mariners, where he impressed with a 4.38 ERA in 125 1/3 minor league innings, primarily in the hitter-friendly Pacific Coast League. His diverse pitch mix, categorized as a five-pitch pitcher by Statcast, includes a sinker, slider, cutter, and changeup, with his fastball and sinker averaging around 94 mph. This versatility and the organization's preference for such pitchers make Castaño an attractive option for the Rockies.
However, Castaño's big league experience is limited, with only one appearance in May of last year. He has been a depth arm for the Mariners, and his performance in the minor leagues has been mixed. In 2024, he posted a 5.19 ERA in Triple-A Tacoma, but his 17.8% strikeout rate and 9.3% walk rate were not impressive. This year, he has been pitching out of the bullpen, with a 1.42 ERA in six appearances, but his strikeout and ground ball rates remain similar to last year. The Rockies can stretch him back out as a starter or keep him in a relief role, providing much-needed pitching depth.
Peralta, 25, was acquired from the Pirates in a deadline deal that sent Jalen Beeks to Pittsburgh. Initially a starter, Peralta showed potential with a 0.94 ERA in 47 2/3 minor league innings in 2024. However, his stock has fallen significantly in 2025, with an ERA above 9.00 in both the majors and minors. His walk rate has climbed to 15.4% in Triple-A, and he has struggled in the big leagues with a 17.8% walk rate and a 15.8% strikeout rate. The Rockies' decision to designate him for assignment is a reflection of his recent poor performance, but there is a possibility that some clubs see potential in getting him back to his dominant form from 2024.
The Rockies' move to acquire Castaño and designate Peralta for assignment is a strategic adjustment to their pitching staff. With a focus on improving their team ERA and addressing their poor performance last season, the Rockies are taking a calculated risk on Castaño's potential while also making room for Peralta's potential resurgence. The team's ability to navigate the waiver process and explore trade interest will be crucial in shaping their future success.
