Extra bases

CHICAGO -- Cubs catcher Welington Castillo did not run hard to first when he grounded out to end the sixth inning Wednesday, and heard a few boos from the fans at Wrigley Field.

"I think that's a one-time thing for 'Welly,'" Cubs manager Rick Renteria said Thursday. "Not only were the fans upset about it but we were surprised by it. He knows. I think that's a very rare thing you saw from him."

• Reliever Justin Grimm had a tough inning Wednesday against the Padres, serving up three runs on two hits and three walks.

"His velocity is still good," Renteria said of Grimm. "We're trying to get what he does in the 'pen into the game. In talking to him [Wednesday], he knows he has to be able to command his pitches. We have to figure out what it is, if it's just emotion once he gets on the hill in a ballgame. Most of his preparation ... he really hits his spots prior to coming into the ballgame. We have to see if we can transition from there to the actual ballgame."

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.