The 2006 Steelers lack the power running game of almost every other season in recent Steeler history. Willie Parker is a slashing Tiki Barber type. I'm sorry, but that's not Steeler football. He's a great back, but the team has not been designed to support such a runner.
More specifically, the offensive line has played much worse this year than in previous years. It used to be that Jerome Bettis would inspire those guys by showing them how to hit the would-be tacklers. Last year Bettis was not an every-down player, but he did some things at pivotal moments in that Super Bowl season.
There's a cascade effect here. Parker runs funny for a Steelers number-one back. The offensive line looks confused for this, and now it's all on them to punish the D-line. The other team puts eight men in the box to stop the run. The Steelers run ineffectively. Now the quarterback must attempt more passes. This causes the o-line, built for the power running game, to work more in pass defense, which was not necessarily their strongest point last year. The quarterback is only in his third year. The wide receivers have not been so good. Everything breaks down.
And for me, it all comes from a single problem. Steeler football is when the other team knows you are going to run the ball, and still you run the ball. This team can't do that. So they can't play Steeler football. The Steelers don't win when they deviate from that formula.
It all comes down to the loss of Bettis and getting away from the power running game. That's how I see it.