That's a concern of mine as well but I don't think it's an excuse where Luck is concerned. I think he has the talent to cover up much of their inadequacies when he is on. The talent around him is better so I expect to see him cut down on his turnovers and maximize possessions. He should get more possessions next season to boot.
I am more concerned about him not being 100% physically and that impacting his on field performance. If healthy, I want to see him reduce his interceptions to single digits and throw for at least 30 TDs. I don't think that is an unreasonable expectation for a QB of his talent, caliber and experience in the league.