Castillo allowed five runs on seven hits and three walks while striking out five in 5.1 innings during Sunday's loss to the Royals. He didn't factor into the decision.
Castillo gave up just two runs over the first five innings of Sunday's matchup and appeared to be in good shape to pick up a win since the Mariners' offense put up eight runs in the top of the fifth inning. However, he allowed five innings in the bottom of the sixth inning, and the Royals' offense ultimately combined for 11 runs during the frame. The right-hander has been inconsistent since the start of September, posting a 3.90 ERA and 1.27 WHIP in 27.2 innings over five starts. He projects to make his next start at home against the Athletics on Saturday.