from the beginning he said that JC leaving was a good decision but that he probably would have made more money by coming back. I disagree but he didn't criticize the decision.
a problem is a lot of people think draft stock is automatically linear with few exceptions. like you're the 25th pick as freshman, if you come back you should get the teens as a soph, and if you come back again you can get the lotto!
you could make the argument pretty easily that JC maxed out his NBA draft stock this season. he put forward the most productive season in the nation, had the #1 PER in CBB. the concerns against him mostly couldn't be resolved by coming back. Chad Ford wrote in his draft post mortem that teams chose big men that were less productive because of they were longer. he can't change that. the concerns about him being able to add a perimeter weren't going to be answered by coming back, he wasn't going to be shooting 3s for our team next year. And then you're just a year older with a sub 7 wingspan and less potential in the eyes of scouts to add a perimeter game. The thing he may have had control over was improving his defense, the other major knock on him, but CBB is horrible officiated and with 5 fouls he has to be overly cautious to remain on the court.
even if you don't max out your draft stock 100%, if you get to 85%+ of your potential draft stock and a first round lock, to me logically it just makes sense to go ahead and go. it would have been cool for him to come back, he probably would have killed it and i think he could have gone late lotto but i don't see that as worth it when he had that chance this year.