Mariners lose 27-year old pitcher to NL West

Mariners lose 27-year old pitcher to NL West originally appeared on The Sporting News . Add The Sporting News as a Preferred Source by clicking here . The Seattle Mariners had to cycle through their organization's pitching recently, and they knew that risked losing one of their arms.

They designated Blas Castano for assignment, and he didn't make it through waivers. Instead, Castano was claimed off waivers by the Colorado Rockies on Tuesday. Roster move: RHP Blas Castaño claimed off waivers by the Colorado Rockies.

— Mariners PR (@MarinersPR) April 21, 2026 MORE: Nathan Lukes is on fire since Blue Jays discovered his vertigo Castano is a 27-year old who hasn't yet pitched in MLB in 2026, but he was on the 40-man roster, and the Mariners needed to make space there, which is why he was DFA'd. The righty made his lone big league appearance last year, allowing three runs in three innings. Castano was really good so far this season at Triple-A Tacoma.

He had appeared in six games (6. 1 innings) and put up a 1. 42 ERA.