The Bills went offense in the first round selecting OT Mike Adams so they focus on the defense here, which was also the focus of their free agency period when they acquired Mario Williams.
SB Nation's Bills blog, Buffalo Rumblings, explains the pick:
After selecting Ohio State tackle Mike Adams in the first round to provide some competition for Chris Hairston at left tackle, there aren't too many more glaring holes to fill on a Buffalo Bills roster that suddenly looks fairly competent.
Wide receiver would be the most obvious remaining issue, but a run on receivers took the likes of Stephen Hill, Rueben Randle, Brian Quick and even Alshon Jeffery off the board before the Bills' second-round selection. There are some interesting prospects available - Mohamed Sanu and Ryan Broyles chief among them - but Sanu isn't great value here, and Broyles isn't what the team is looking for in a No. 2 receiver. Coby Fleener would have been a consideration - he'd add a second receiving threat to the mix, after all - but he, too, was gone.
The guy I really wanted to take here was Lavonte David. The Bills have very weak linebackers, in my opinion; beyond the barely-reliable (from a health and age standpoint) Nick Barnett, there is very little youth or speed, and particularly none to be found when looking for both in one package. I liked David as a down-the-line replacement to Barnett - a weak-side linebacker with the coverage ability, athleticism and instincts to man the middle on passing downs, and with the sideline-to-sideline range that the team desperately needs. Alas, Carolina snagged David at No. 40.
That left me three choices: reach for a receiver I don't like (I've done enough reaching this year), reach for a linebacker I don't like (see previous), or just take the top guy on my board. Hence the selection of Chandler Jones, who only narrowly beat out Marshall defensive end Vinny Curry and Central Florida cornerback Josh Robinson for the honors.
Yes, the Bills spent a combined $115.5 million on free agent defensive ends Mario Williams and Mark Anderson, but that doesn't mean that they should be done re-tooling the position. For one, the team's two primary backups at the moment (assuming Williams and Anderson are destined to start) are Chris Kelsay, who will turn 33 on Halloween, and Shawne Merriman, who hasn't been Shawne Merriman for five years now. There is no youth. There is still not enough depth to create waves of players that can cause havoc; in a division that features Tom Brady, the Bills need to replicate what the New York Giants have done defensively in trying to beat him consistently.
Jones, who is one of the hottest names in the draft class at the moment, did not have a particularly productive three-year career at Syracuse, but he does have some advantages working in his favor. For one, most scouts acknowledge that Jones has only scratched the surface of his playing potential. He also offers some versatility, having logged some time inside in college. Dave Wannstedt, who coached at Pitt through 2010, will have a strong working knowledge of Jones, having played against him for two seasons. Perhaps most importantly, Jones can be groomed, as at best he'd enter the 2012 season fourth on the end depth chart (behind Williams, Anderson and Kelsay), and playing primarily a part-time role while his game is fine-tuned.
The value is good, the prospect is good and philosophically, adding another pass-rushing threat makes all the sense in the world. I took a lot of heat for the pick of Adams - justifiably so, as I hated it more than most - but I'm much more comfortable making this pick. Jones would be an excellent investment for Buffalo in Round 2.