Castillo allowed six runs on six hits and four walks while striking out four in four innings during Sunday's win over the Mariners. He didn't factor into the decision.
Castillo was relatively effective over his first 11 appearances (four starts) in the majors this year, posting a 2.97 ERA and 0.99 WHIP in 30.1 innings prior to Sunday's start. He gave up just one run over the first four innings of Sunday's matchup but struggled mightily in the top of the fifth inning prior to his removal. It's not yet clear whether Castillo will make another start for the Royals over the final week and a half of the regular season.