Blue Jays manager John Gibbons said Monday that he will platoon Colby Rasmus and Darin Mastroianni in center field for a while until someone gets hot. Rasmus has 12 homers and 27 RBI over 54 games this season, but he's batting just .216/.270/.463 overall and is hitting .167/.286/.333 versus lefties. It's worth a shot, but Mastroianni (a career .218/.283/.300 hitter over 290 plate appearances) is unlikely to do much damage.