I really believe that a Zeller would be just fine as our C in a rebuild. Look at all of the tams that built from the PG/wing position... without a great center. Zeller is serviceable, and we might add a beefier guy later, but give me three really good young (not star yet) players at the PG/sG/and SF and then let KO, Zeller play off of them.
If we are not looking for a quick turnaround, I would just as soon let Green and Bradley go in trade (and of course nelson, Bass) ... Just roll with Young, Turner, Smart, KO, Sully, Zeller, Crowder, Pressey, Wallace (mentor)... (and whatever young or "cuttable" players you take on.
It might be ugly, but at least Brad could play a set rotation and build some continuity. Then we will know what we need most in the draft next year. Why not?