Bill Simmons wrote a few seasons ago that he thinks home field advantage has disappeared. I do agree that home field isn't as big as it used to be for all the teams as a whole, but there are certain teams for which home field matters significantly, and I think the home-road differential for these teams is being underestimated.
This line has moved significantly as it opened with the Steelers -5. People are jumping on the fact that the Steelers' offensive line has looked horrible, Big Ben is hurt, and Chris Johnson finally having a 100 yard game. Well, the 100 yard game was against the horrible Browns, and the Steelers are really good at home. Given that the Steelers do have a home field advantage, the line suggests both teams are even, and I don't agree with that assessment.
Another line that has moved a lot from the GB-3.5 that it opened at. Atlanta is a much different team at home, and Green Bay hasn't been as dominant on the road. I expect this to be a competitive game, and I don't think it would really surprise anyone if lAtlanta won this one outright.