Thomas Jones got what appears to be a minor rib injury. They taped him up, but I think that by the time he was back they'd decided to go to Peterson and Benson.
Peterson was in before Benson largely because of their field position at that time. They didn't seem to want Benson in while they were in position to potentially give up a safety. Benson had 2 decent carries, I believe, and one excellent carry. I think he's probably as good as people thought he'd be, which is to say, better than average, once he's given a real shot. But T Jones is still the man. 73 rushing yards and 25 receiving yards, in an incomplete game.