They're definitely good, but not unbeatable. I know of 2 teams that COULD beat them if Oakland was on the road. Beating them at their house or a neutral site though, that would be tough....
Having seen both Alcoa and Oakland, I could see that IFL game being a nail biter. The only reason I'd pick Alcoa in that one is because they finally found a QB that could make Oakland pay. Oakland wouldn't run all over Alcoa either and that hybrid Wing T plays right into Alcoa's strength.