Don't know why others doubting this guy early. There are lots of room for improvements if ever he will have difficulty for his early seasons. And yes, as a big man, there will be a point that he will clash with the likes of Joel Embiid and Greek Freek but as long as he tries to improve his defense anytime, then much better. No need to literally expect him that he can able to stop those two always.
I've also seen some highlights and he looks good with some post moves but people that tall don't usually last playing multiple physical games in a year. It's his durability that's being questioned.