Mets left-hander Johan Santana threw off a mound in Port St. Lucie, Fla., this week for the first time since undergoing Sept. 14 surgery to repair a torn anterior capsule in his left shoulder. Santana attempted 15 throws from the mound without issue. The Mets have eyed July for Santana's return to the major leagues, but he still has significant hurdles to clear.