We really are desperate for an athletic rim protector. I like Zeller, but he seems best suited as a nice back-up at the C position. Sully or KO, Green, filler, and picks should be able to net us something pretty decent.
If we trade one of KO or Sully, then I am actually for keeping Bass as our backup PF. Zeller and Bass would make a formidable duo off the bench. I think our guard rotation is more than enough to compete and Green is currently showing why he is an above average SF or above average trade asset.
Honestly, with a very good rim protector, we could be very competitive with the ability to continue to improve.