Pretty sure its been covered that Defenses are playing 2-deep safeties against the Bills for the express purpose of taking away the big play.
As for the D....Milano was its main big playmaker for sure.....the D-line is supposedly full of playmakers, but they are not producing at a level they need to be.
However, holding the Bengals to 24 points with the amount of injuries on that side of the ball is just about as much as you could ask....it should have been enough to win if the O(particularly JA) would have played up to the level they are capable of.