Well, then you must only watch box scores and not games. He has absolutely shown talent when on the court. Is he a perfect player? No. Does he need to get in better shape and gain some quickness? Yes. Is it possible that he'll never be quick enough to contribute to a playoff/contender? Yes, absolutely.
But not developing a young asset, and not giving him ON COURT TIME DURING games, is a waste of that asset. Regardless of whether or not he fits our future plans, WE ARE WASTING AN ASSET.
So, again, this line of thinking is stupid. There is NO EXCUSE for not developing Zizic with IN GAME MINUTES. None.