I had the same thought, no disrespect intended to their coach. I've had that happen a handful of times over many seasons, teams that win that don't quite add up to me. Sometimes you just put the pieces together in the right way, and it might not be obvious why it is the right way. I mean they won all season when they played good teams, so I don't think the NT was a fluke for them.
But I'd love to hear someone explain why they're better than I think they are. I used to think these situations suggested there was a hidden "player chemistry" factor, but I realize that's probably not true.