No doubt coaching is critical, both at the top and in the staff. I think there also is a lot going on with "team chemistry" as well, something that may be more random in nature. I'm not sure a great coach can win an NC these days with mediocre recruiting, say 25th in the 247. I think they can be 11-2 obviously, really good years, but it's tough to make the FF and win without top level coaching. I think Clemson had some classes in the teens when they won the first time.
And some of this of course is finding a QB who is way better than expected, a Baker Mayfield type.