I don't recall calling the Patriots defense the "best", I'm just pointing out it does more to help them win games. On the other hand, the Steelers philosophy on defense is "tackle the catch." In the last few seasons, the Steelers defense has been hoping the other team's offense makes a mistake rather than forcing the issue. Essentially, they're playing scared, or playing not to lose.
Of course, it doesn't help when the offensive play calling goes something like this:
1st down: Run up the middle - no gain
2nd down: Run up the middle - no gain, maybe even a loss of a few yards. Or maybe we see a bubble screen that gets tackled for a loss.
3rd down: Ben help!
Ben actually was bailing them out from that in the first half of last season as his 3rd down passer rating was the best in the NFL I believe. However, that kind of play calling isn't sustainable. It also goes against the notion of protecting Ben as on third and long pass rushers can just pin their ears back.
Last year's playoff games, most of them being higher scoring, should have shown the Steelers how outdated their philosophies are.