He's a great coach because you can plug and play pretty much anyone on the field and odds are damn good they'll still win the game. His players respect him and his program, generally behave themselves off the field (unlike the Chiz who has players publicly biatching about leadership and a wife who's spouting off about satan on Facebook), and show up to do their jobs regardless of personal opinion. They are proven to be prepared for life after the NCAA and don't collapse immediately like just about any player who's come out of Mack's program.
He doesn't rely on one player to carry the game and those coaches who do are less than adequate because the entire idea of coaching is that you create and sustain a team, not a supporting cast for one player who happens to play at an extremely high level and has a team who falls apart should something happen to them (Cam, Manning's Colts, etc). I wouldn't call Cam or Colt "gimmicky" (a term much better suited for a Tebow type) but their coaches had lucklaster programs both before and after them (well, Vince and Colt for Mack). Hell, Mack Brown kept vince on the bench in favor of Chance Effing Mock after Vince had already proven his skill on the field. He's like Jerry Jones actually being a coach rather than pulling his coach's strings.
When you have as much talent and the world class resources Chizik and Mack Brown have, you should be a 1-2 loss team at most. Consistently. If you lose more than that, you aren't a good coach and you lose to teams like Ole Miss and Iowa.
+1. I don't even need to respond because you hit the nail on the head.