What Renteria noticed was how Castillo would go to the mound to get the pitchers to slow down the pace of the game and give them a chance to regroup. Castillo is in charge of a young bullpen.
"They're young and don't have a lot of experience," Castillo said. "If they shake anything off, and I think it's the right pitch, I just shake my head, like, 'I got it, let's go. Just follow me, we'll be fine.' We throw the pitch and throw it with conviction and we get the out, and that's how trust comes."
Castillo would like to improve his batting average -- he was hitting .248 heading into Thursday's game -- but he's spending most of his time on the pitchers.
"I've been working really hard on game calling," Castillo said.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.