Castillo (9-4) took the loss after yielding six runs on eight hits and two walks while striking out six over five innings Friday night against the Rockies.
Castillo was hit hard from the very start, surrendering three runs in the first inning followed by three in the fourth prior to being lifted with a four-run deficit. He fired 61 of 97 pitches for strikes and threw first-pitch strikes to 15 of the 25 batters he faced. Despite a rough outing, the 26-year-old has been impressive for Cincinnati this season, posting a 2.71 ERA and 1.15 WHIP with a 144:59 K:BB across 123 frames.