Bills have a very good defense Rams have a weak defense. Yes Rams offense is much better and may even it out but looking at both teams OVERALL stats I don't see any advantage for STL.
Rams are on the road in the cold. Not freezing but still a big advantage for the Bills.
Rams bad as a non-conf road fav. Miami got their only win of the season (and in convincing fashion) at home vs the Rams.
Bills have played a tougher schedule IMO and I think that always helps.
If this game was in the dome and Rams were 10 pt favs I prolly wouldnt play the Bills but at home, with a very good defense I think the Bills are a good play. I do worry about what loophole said about public dogs playing bad but still think Bills are a solid play as long as they haven't completely given up on the year.