Just as I had hoped, someone posted the clip of Sean Canfield's 18 yard run that ended up with him sprawling on the turf. Riley said we would find out more on the injury tomorrow.
You may think this was cheap, you may not. If you ask me, it typical for the USC defense. Many times they were leading with their helmets when it was completely unnecessary. There is no reason to risk injury like that. It's hard to tell if this USC defender was leading with the helmet or not. If you look closely, the contact may have been made with the shoulder pads.
Sean was clearly sliding into the turf, and the hit was clearly late and unnecessary.
But looking at the positive, that was one of Sean's better decisions he made all day. He saw the rush, and made a quick decision to bail.