The rotation should be expanded, absolutely. The problem there is, Mo doesn't know what he has and is still experimenting.
Nailon turned out to be a bust, and IMO, Mo was expecting him to be their 6th man. As it is either Korver or Salmons make much better 6th men.
Cheeks is overelying on AI and CWebb, which is understandable, but a mistake non-theless.
The thing is, no one else on the roster is ready to be a go to guy. Korver and Igoudala aren't ready for that kind of pressure, and neither is Salmons.
All this was forseeable from the begging, that the Sixers would take time to develop into a good team. The pieces are there, but most of them are too young and inexperienced. I would expect a number of setbacks ahead. They are improving, but they are a long way from being an established team with that knows what to do on a nightly basis to win.
The Sixers won't be a finished product until Iverson stays within the offense 70%-80% of the time. AI's tendency is to take matters into his own hands, and that's the easy way for him. But for the team as a whole, they all need for AI to work harder on setting up other players, penetrating to pass instead of taking it to the rack. And the other players, particularly Iggy and Korver, they need to want the ball more and to move aggressively without it, demanding the ball as they cut into the lane.
The discipline of forcing AI to play team ball on offence is going to be very hard for him. Particularly when other teams turn up the heat defensively, he will want to just put his head down and go. That is where the Sixers become a weak, unbalanced team. It will be hard to criticize AI for doing what he has allways done, but Cheeks is going to have to impose his will, so that the first instinct when the pressure comes is to run the offensive sets.