I think we have a lot of depth there, but no frontline stars . . . if they can just do their job, the over-all defensive talent will cover for them. Fortunately, the 4/3 is not a linebacker dependent defense, and considering the talent (or, lack thereof) at linebacker, this was probably a consideration--not the only--in switching back to the 4/3.
By units, the Bills defense, strength to weakness scale:
(1) Line = Very Strong;
(2) D'Backs = Strong [not outstanding, but capable];
(3) Linebackers = Average [we hope].
By the way: I believe this is my 1,000 post - this is a special day!