Now wait a second, put him in there with the first team offense (I know I know, also means he's going up against first team defense) and I think behind the offensive line with Zeke carrying the team on his back we would be just as fine with Cooper Rush out there as we would with any other backup. If he's capable of making some good throws here and there, can get into the end zone a couple of times a game, and doesn't turn the ball over, I don't really understand what more you would expect out of a backup. As a matter of fact, name one backup we've had since Kitna would get through a game without turning the ball over multiple times.
I'd say he came out a little cold yesterday, definitely didn't put some balls on the money. But at the same time it's the first game of his second preseason and I think he just got cold feet (and still put up OK numbers). I think the backup offensive line was also making him pretty uncomfortable. If he doesn't improve a lot then he might just be a career backup, but the #s and eye test (unless he's regressed from last preseason) tell me he's good enough to play backup and get a team some wins.