Since the OP mentioned the last five years, I thought it worthwhile to look at those years. Obviously, the big shortfall in BB's coaching over this time is that the Pats haven't won a Superbowl. We all know that. That's a disappointment to us as fans, and I'm sure BB sees it as a failure to achieve his goals.
Let's look at the five teams over that period of time that have won Superbowls, the Packers, Steelers, Saints, and Colts, including the 15 games of 2011:
Packers: 63-33, four winning seasons.
Steelers: 62-33, five winning seasons.
Saints: 61-34, four winning seasons.
Giants: 56-39, four winning seasons.
Colts: 63-32, five winning seasons.
You can see they're all pretty much neck-and-neck over five years, except for the Giants, who are 5-8 wins short of the other four Superbowl winners.
Here's the Pats:
Patriots: 75-20, six winning seasons.
The most remarkable thing was that I first did this compilation not including the 2011 season, and over just the previous five years the Pats had more wins (or the same number) as the other teams had over six seasons. In other words, the Pats have an entire season-of-wins advantage over the other five contenders.
This is a coach and GM that needs to be turned out to pasture? I don't think so. Let's hope for the best in the playoffs.