Within the past calendar year, the Buffalo Bills have made three prominent free agent signings during the NFL's annual March spending spree. All three of them were pass rushers, all were picked in the 2006 NFL Draft (two in the first round), and all three have ties to each other in one form or another.
It's a good thing the Bills made those signings, because as it stands today, they've only got one additional pass rusher on the roster. Let's take a look at Buffalo's four edge defenders within the context of the "hybrid" defense, which defensive coordinator Mike Pettine plans on employing.
Mario Williams (6'7", 292)
We know what Williams is capable of athletically: he can stand up and drop into short zone coverage. What a player can and should do, however, are very different things. Pettine comes from a New York Jets team that loved to overload on blitzes, so you'll see Williams in space from time to time without a doubt. The overwhelming majority of the time, however, he'll have a hand in the dirt rushing the passer.
The easy comparison to make in terms of his role is Terrell Suggs in Baltimore; he's athletic enough to capably play end or outside linebacker depending on the look, but Baltimore asks him to do what he does best, and that's rush the passer. We envision Williams in a similar role - and since his preference is to play on the left side, he'll likely be over there more often than not, as well. In ideal situations, he'll be lined up on the weak side of the formation, away from tight ends that can aid tackles in their blocking assignments.
Manny Lawson (6'5", 240)
From a functional standpoint, Lawson is sort of the antithesis to Williams - he can probably line up in a three-point stance as an end in many looks, but his lack of bulk (and corresponding better range) make him better suited to playing mostly a linebacker role while occasionally putting a hand down.
Lining Lawson up on the strong side of the formation makes sense, whether he's playing end or outside linebacker. An outstanding athlete with ample experience dropping into coverage, having him lined up across from a tight end could be a potential boon for the Bills, as he can either cover the tight end - he's got the straight-line speed and the length to hang with most tight ends down the seam - or rush. As such, it's easy to pencil him in as the SAM linebacker-pass rushing hybrid that we've been talking about for weeks. In 4-3 looks he'll play linebacker, in 3-4 looks he'll play outside linebacker, and in nickel and dime looks he can rush or cover from the end position or line up behind the line of scrimmage and cover. He is, in essence, Pettine's most versatile chess piece.
Mark Anderson (6'4", 255)
There are athletic and physical build similarities between Lawson and Anderson, but the two players are not likely to be used the same way on defense. For one, Anderson does not have anywhere near the coverage experience Lawson does; he's also not quite as explosive an athlete as Buffalo's newest pass rusher.
A team can never have enough pass rushers, however, and Anderson is more proven in that particular area than Lawson is. He's not stout at the point of attack and can only be utilized in coverage the same ways that Williams is, so to my eye, Anderson is a part-time defender, much like he was in 2011 with the New England Patriots (12.5 sacks in 19 games). He can play the nickel and dime role at end that Lawson could conceivably play, and the team can also use him as a pass-rushing end in heavier-front (i.e. non-nickel or dime) defenses in certain situations. Anderson has always been at his best (and healthiest) as a part-time player.
There's really only one other player on the roster at the moment that can capably play an edge-rushing role; that's 6'0", 250-pound fourth-year pro Arthur Moats, who does not really fit the profile of the bigger, rangier edge defender that Pettine is looking for in this defense. Kyle Moore (6'5", 263) remains an unsigned free agent, but strikes me as a rotational/situational rusher much like Anderson. Depth is a concern at this position as we move forward into the off-season, even after the Lawson signing.