The rookie right-hander, who had thrown 103 pitches in only four innings, stays in L.A. to undergo MRI exam. 'Any time you say a guy's elbow hurts, it's fairly scary,' Manager Don Mattingly says.Rookie right-hander Rubby De La Rosa , one of the few pleasant surprises in a season full of despair, was placed on the 15-day disabled list Monday with a sore elbow.