I view it all about statistics. To win the SB, you have to give yourself as many opportunities as possible to get there. Of course there is that anomaly, like the Cards who have a somewhat flash in the pan and get there.
But, there are so many factors that go into winning SB's. Having a franchise QB and a good coach are a start, but thats not enough. Otherwise, we'd see a Pats dynasty like no other.
Statistics are also a reason why I'd be against Cowher, seeing as the "rule" comes into effect here.