Deontay Burnett practiced over-the-shoulder catches with a fellow receiver after USC’s practice Tuesday. Burnett would run in place, look up for the ball, catch, then lob one back. The throws to Burnett came in cleaner than the ones he threw out. They spun in a tighter spiral. They hit Burnett just where he was expecting. His partner was Jalen Greene, after all. Greene had been a quarterback once. Now he might be USC’s most important question heading into the season as a receiver. The Trojans’ offense will depend on how well the converted quarterback develops into a legitimate threat on the perimeter. As USC cycled in receivers during training camp, Burnett and Greene were the mainstays. They ran with the first team from start to finish. Burnett was not a surprise. Greene’s emergence was less likely. For a while, his greatest appeal was as a utility man. Greene signed with USC as a quarterback. He played there his first year, when he redshirted, but his accuracy was dicey, and he saw scant opportunity for playing time with Cody Kessler returning and Max Browne ahead on the depth chart. He asked then-coach Steve Sarkisian if he could switch to receiver.