As a Buckeye fan living in Ohio, I can tell you Kosta was no where near ready for the NBA when he left OSU after his first year. He was easily muscled out of the paint and was a terrible defender. He had a pretty solid outside stroke, but that was about all he could do.
It has been a few years so I'm sure he is much stronger and has worked on his deficiencies, but he had a long way to go and it is tough to get there when you don't get any game action.