re: Which players back from injury will have the biggest affect on the game?

I don't ascribe to the notion that running backs significantly contribute on "punishing carries" for two yards. That's a prescription for three and out against Ala.
We cannot give away possessions agaisnt a top team, even if one expects a very low scoring game and we have a great punter (which I do and we do, respectively).
There is also opportunity cost in leaving in a QB who is cold. We did that against a weaker Georgia team. Inb saying this, I acknowledge that the back up QB must not contribute to turnovers.
That's the trade off.