He's had perhaps the toughest type surgery there is to recover from. He's already admitted in interviews that he's lost a foot on his vertical jump. He tested at 36 inches in the combine prior to surgery so he's not anything special right now. From an eyes view, he's also not nearly as explosive with his defensive movements as when he was at OSU. The microfracture surgery recovery, if successful, usually takes around two years to come back. No telling if he'll ever fully recover, but nobody would expect any more of a physical recovery than what he's shown so far. So, his new 'limited' ability along with the new pace and skill level of the NBA is a bunch of 'learning curves' that are all slowing him down.