I actually really like Zeller. My biggest issues with him is
1) he got mandhandled by bigger guys too often on rebounding situations, I mean, embarrassingly tossed around that it was hard to see how he could handle the much stronger guys in the NBA night in and night out. It was appropriate to call him soft. He didn't look bigger or stronger his senior year but he seemed to hold his own physically better his senior year. That's more promising
2) he is a horrible passer out of double teams, as turnover prone as you can get in them.
Otherwise, from the day he enters the league, he's going to be a top 10 athlete amongst C/PF. He runs the floor incredibly well and can finish after catching the ball at top speed which you just don't see seven footers do. He's a honest to goodness track athlete.
And then there is his offensive game. He's got a post game he can go to but what he's going to be allowed to show more in the pros is his good outside shot. He didn't shoot it from outside too often in UNC's system but he made the majority of those he took and his stroke is good. He's going to be a very good pick and pop big man. A C/PF who is capable of averaging around 16 points, with a solid amount of rebounds and is willing to take charges...that's a very solid player to have.