The only penalty that really stopped a Seattle drive was the holding call when Stevens caught the ball at the one.... and I admit that was a huge play in the game... but it was a judgement call.... not a totally blown call as some have said.
Dude got beat enough that he had to get into a position where a judgment holding call could be made and it was.... had the call not been made, I certainly wouldn't be sitting here bitching about it.
And after that penalty, the Steelers got a sack, the Seattle inexplicably ran Alexander on 2nd and 30 or whatever, then Hass threw his terrible pick. So again, Pitt was helped by the judgement call, but they also made the plays after that call and Seattle didnt.