It seems logical that he was brought in to be the 3rd down back, so really the RB3. But it's also valid that there can be injuries to Akers or Henderson that make him the RB2 for one or more games.
But honestly, I wouldn't dismiss that he needs to beat out Funk first for the week 1 RB3 role. He's going to have to play special teams to be a game day active at all. And there's still Jones and Calais hanging around.
