If you liken these teams to fighters, particularly MMA fighters it's like this. The Pats may not look that flashy but they are proficient if not very good in all areas. This allows them to defend your greatest strength and attack your greatest weakness. While losing Bell was huge it is hard to picture him having a huge day. They were full committed to stop him and it didn't appear the Steelers were going to pass to run.
The Steelers on the other hand are the classic we gotta be us fighter. They couldn't come out and do what was necessary to make Brady uncomfortable and get him off his spot which was play man and bring pressure. That wasn't them and therefore was off the table.
The Steelers on the other hand are the classic we gotta be us fighter. They couldn't come out and do what was necessary to make Brady uncomfortable and get him off his spot which was play man and bring pressure. That wasn't them and therefore was off the table.