His impact on defense is probably on par with Okafor's at Duke. What keeps him from being an Okafor-type negative player overall is his ability to fit into an offense and excel with high usage without killing the offense of everyone else around him. I think he's a major plus overall but I wish he would not be so harmful on defense.
Didn't think this day would come, but I look forward to next season with Bolden at center, assuming Bolden isn't so stupid that he thinks his own post ups are better than anything Tre, Reddish, Barrett or Williamson would otherwise do on offense. Should be a low usage, high efficiency rebounder on offense, and solid on defense. Hopefully, he comes back.