Of immediate concern is the unfamiliarity of Orton to the Bills offense. (hold the joke about having only 4 plays to run). The two backups who knew the offense are not on the active roster. Till Orton comes up to speed (which could take a few weeks), we better pray like hell that EJ doesn't get nicked up (not that I ever want him to get hurt but from a team's perspective, especially not in the next few weeks).
The trick in this situation is that wanting to protect EJ could result in a game plan which is too safe. I would have liked Whaley to keep Tuel till such a time as Orton is ready. Then stash him away on the PS. As it stands right now, the offense's hands may be tied with respect to how aggressive they can be.