I'd say he got buy in and culture the first ...3 years of his tenure at minimum. Even after that, kids were bought in they just started to lose, he failed to recruit well enough and then things really unraveled. He "was excellent winning that championship" is not something you say about someone who just isn't cut out for coaching.
You can't view the first 3 years at least of his tenure and say "coaching isn't for him" but you definitely can say he failed at THIS job, at THIS time in his life. It was his first HC job, by the way. And Jim Calhoun thought he had the qualities necessary. That doesn't mean he didn't fail, but you're saying a blanket statement that he is not cut out for coaching, naturally. I totally disagree with that.
Also, as many have pointed out, the NBA has a much different job description, where he can relate to pro athletes, more than likely, better than he did to college kids. He doesn't have to be on the road recruiting and scouting what players will end up being good. He doesn't need to construct the roster properly. Even the Xs and Os at the NBA level I would say are less important, just because the good players make plays more often than not.
Whether it comes across as too pro-Ollie or not, I don't care. I was really sad to see him go but knew he needed to, and I am all in with Hurley. I have never gotten into the back and forth about Ollie. He failed here ultimately, but I would not go as far as you have gone in your statements about him.