Rockies add depth by claiming Mariners pitcher off waivers

As the Colorado Rockies try to work their way back towards contention, or at least a winning record, they’re willing to turn over any rock for potential talent. Colorado is hoping they found a diamond in the rough with their latest move.

The Rockies have claimed right-handed pitcher Blas Castano off of waivers from the Seattle Mariners and optioned him to Triple-A, the team announced. In turn, Colorado has designated left-handed pitcher Luis Peralta for assignment.

Castano appeared in one game at the major league level with the Mariners in 2025. But he allowed four hits and three earned runs over three innings and was promptly sent down. The right-hander has looked much more impressive to begin his 2026 campaign, holding a 1.42 ERA and 4/1 K/BB ratio through his first six games.

Over his entire 147-game minor league stint, Castano has recorded a 4.44 ERA and a 513/208 K/BB ratio. He’ll now be reporting to Triple-A Albuquerque. The righty holds a 4.96 ERA and a 178/76 K/BB ratio over his 51 games at the level.

Playing at Coors Field is a difficult task for any pitcher. However, the Rockies’ bullpen has been able to slay the beast thus far in 2026, as they rank seventh in the league with their 3.49 ERA amongst relief pitchers. As the Rockies try to carve out a successful season, they’ll be continue to rely on that surging bullpen.

Castano is looking to prove that he deserves another major league opportunity. His start to 2026 has been strong, and it clearly caught the eye of the Rockies. If the right-hander continues his hot streak in Albuquerque, perhaps he soon gets the major league call.