My feeling is that Stepp is a lock for the #2 spot because he's a different style of back than Morrison and Ervin. The real battle is for the #1 spot, with the loser consequently ending up at #3. Last week it sounded like it was Ervin, this week it sounds like it's Morrison.
I think the situation will be fluid for the first few weeks, whether they want 'RB by committee' or not. Oklahoma might end up being the real decider, I mean obviously if one guy looks good running against them, he'll probably be the starter for the rest of the season.
Of course, all of this depends on injuries, and we've got a whole room full of guys with an injury history...