What is your definition of great x and o's?
May just be semantics on my end but I don't see guys like Calipari, Roy Williams, Self, Matta as great coaches. I think they are good coaches though.
Izzo now that's a great coach
All four of those guys you named are outstanding coaches. John Calipari would beat Bruce Weber with Kansas State's roster and he would beat Bruce Weber if you gave Bruce Kentucky's roster. Or pick a different guy with a "coaches coach" reputation who has a spotty track record.
Cal pre-Camby at UMass, Self at Tulsa, Matta at Xavier, all of those guys have proven what kind of coaches they are, and when you add in their ability to not just get elite talent, but have those kids ready early and make their inexperienced teams into low-mistake units who share the ball, play both ends of the floor, and understand and care about the little things, that's why they're superstars in the profession. The Josh Pastners and Rick Barnes' and Lorenzo Romars of the world get exposed quickly, even with their McDAA's.
I think I'd probably have Izzo at the top of the heap, but he's no stranger to elite talent and doing those things I mentioned either.
Being able to score a 1600 on your basketball SAT doesn't mean anything if you can't express it on the floor through the work you've done with your players. It's not how much you know, it's how much you can teach, and how ingrained and instinctual that teaching is when the circumstances get tough.