4. New England Patriots, Weeks 16 and 18
The New England Patriots have always had a great defense under Bill Belichick, but there is a new head coach in town with Jerod Mayo. Mayo is a Super Bowl winning linebacker who played under Belichick in his time in New England, so there shouldn't be much of a drop-off at all with this new regime.
Even though the last few years for Belichick and these Patriots weren't successful, they always were well disciplined on the defensive side of the ball. The Patriots brought back their better defensive players, while also simultaneously getting back players from injury last year.
The two most notable are Matthew Judon and Christian Gonzalez. Fortunately for the Bills, they did not face these two last year. Even though Belichick is not at the helm, I expect Mayo to keep this defense top-notch.
Not only can they be a potential Top-8 defense in this league, but the Bills also face them twice a year and know all too well what Josh Allen and this offense can do. Because of that, they are not going to be easy to face, especially after facing them twice in the last three games of the season.