1) Think about it. Herrera is our 8th inning closer. Holland is on DL. That leaves Davis as the 9th inning closer. Losing Herrera on his second pitch over something like that would be crazy.
2) It had started raining. His hands and the ball were wet. (It was not raining when Cain got hit in the first inning)
3) Herrera was motioning to his head by referring to it as a dumb play on his part.