Quarterback Mitch Mustain estimates he got 10 phone calls from other programs after NCAA sanctions were announced two months ago. Everyone knew the senior was blocked by sophomore quarterback Matt Barkley and probably would play his entire USC career as a backup, so some coaches used the cover of the Trojans’ bowl ban to do a little late-career recruiting. His decision to stay was a calculated one. Mustain has hopes of playing in the NFL and USC runs a pro-style offense. “You’ve got to be able to get on the board in front of GMs and coaches come January, February and March and explain what you’re doing, explain protections, that you understand where the O-line is going, that you can command an offense,” Mustain said. “I feel like this is the best place to learn that.” Mustain, once ranked as one of the top high school player in