Before I get bashed for hating on PIT, let me say I think they have a good team and a lot of top level talent. I think their coaching sometimes leaves a lot to be desired, but the team itself is most likely more talented than NE's.
But as the Steelers offense and defense goes, comparing the Pats actual results over the season, NE's offense still scores more than PIT's does and their defense allows fewer points than the Steelers does. Based on points scored or points allowed, NE has ranked higher than PIT in both categories for 5 straight years. That doesn't even take into account that NE has had their way with NE over that time. With all the talk of the Killer B's and how unstoppable they have been, the Pats have been able to score more (even with Gronk and Edelman out a ton).
If these two meet again, I think things will be much tougher for PIT playing in NE than in PIT. Not that prior results impact future games, but the average game score between these two in the BB/TB era when playing in PIT has been 27-24 in favor of New England. The average game score playing in NE has been 37-19 in favor of the Patriots. That's more than a two TD difference.
To be clear, PIT certainly could win if they play well, the ball bounces their way, and they don't make dumb mistakes. All I am saying is that historically the Steelers have had trouble playing in NE.