Castillo (1-4) earned the win Thursday against the Astros, allowing three runs on four hits and three walks in 5.2 innings. He struck out six.
Castillo was working on a bounce-back start Thursday, giving up a lone run over his first five frames, but the Astros got to him for two more runs in the sixth inning to make his line more middling. The Mariners might have left the 33-year-old right-hander in the game for a bit too long considering that the hurler tossed a season-high 108 pitches. Castillo has now yielded at least three runs in three straight outings and six of his last eight, posting a disappointing 6.34 ERA, 1.57 WHIP and 43:16 K:BB over 44 innings in 2026. He's tentatively lined up to piggyback with Bryce Miller early next week versus the White Sox, which would mark Castillo's first career relief appearance if he works as the secondary pitcher.