It doesn't matter. He went and had a pro off-season once he couldn't play anymore and he showed he's talented.
If teams are stupid enough to pick him later than he should that's on them. As long as he is in the league and gets a chance to play that's all that's relevant. Giannis isn't hurting from being the 15th pick. As long as you have opportunity.
Pro off-season can only get you so far when 1. He's only played a few games since graduating high school and 2. He is more than likely not going to be able to contribute any meaningful minutes right away wherever he gets drafted and 3. He hasn't been able to do anything to erase or ease the mind of scouts and doubters who question his long term potential.
It's literally going to be over a year and a half before he actually gets to play meaningful basketball again. The people in his circle fukked up big time.