IMHO the singular, critical matchup is Pats OL vs Rams DL. If the Pats OL can provide Brady the kind of protection they did against the Chiefs as well as open some running room for Sony, Rex, White? The Patriots at minimum will be up by or within a score in the last couple of minutes.
Next, if the first half AFCCG D shows up to Atlanta for at least half+, this will be the Patriots' game to own (or not own).
In KC in January may, outside of Denver, be one of the most hostile places for an opposing team to play in. For the most part the team looked mentally as ready as could be hoped for. Hard to see this BB coached, TB led playoff savy team not looking as good if not better in a neutral site dome (if the OL pitches another solid game).
We'll see...