Zeller...well if he couldn't crack 30 minutes playing on a rebuilding Cavs team without Varejao, I am not too confident on his abilities.
A couple of points.
1) Cleveland was NOT supposed to be 'rebuilding' last year. They were trying to make the playoffs.
2) Zeller came into the season with high expectations after a strong summer workout program to build muscle mass. He promptly got appendicitis and had to undergo an emergency appendectomy in October. This caused him to lose a lot of the strength and mass that he had put on. It's not surprising that he played much better as the year went on. His numbers after the AS break were much better.