I'm not the best dissector of plays, but Robey-Coleman was the one who got burned a couple times, as far as I could tell. Shields had that clutch deflection in the endzone.
And keep this in mind: while we would rather have Peters and Talib in there, the backups managed to hold the Chargers to 3 points after the two starters went out. And that's after Rivers had already established some success with the pass. So... I think the backups are going to be ok. I really do. Shields will be good. NRC and Hill will be serviceable. Cousins is not going to destroy us.