Being head coach in the NFL is probably the toughest of all coaching jobs. It's by far the sport where coaching matters most, and it's kind of a young man's game. Remember when they brought Joe Gibbs old ass out of retirement? It did not go well. I wouldn't want BB to come in and coach my team today.
Yeah, there's a point where a coach has just gotten too old and/or stuck in his ways.
As much as I love me some Pete Carroll, now that he no longer coaches the Seahawks, I'd have to at least think twice about hiring him. He's what? 72? He has more energy than some of the players, but he's been showing signs of being stuck in his ways the past few years.