Well, the quickest way back would be to sign Greg Oden to the bi-annual and for him to actually stay healthy. Oh, and bring back Pierce and KG.
Oden, KG,

, Melo
KG, Sully, Green
Pierce, Green
Lee, Bradley, Terry, Crawford
Rondo,

and 3 more guys
Yes, I know I left out Bass and I'd trade him if I could. I'd trade Melo, Lee, Terry, Crawford, and/or Bradley, too, for a good starting SG, a real backup C and real backup PG.
And Yes, I know it is a long shot that Greg Oden could stay healthy for even one entire season. If he did, though...