Pettine was last with the New York Jets, coaching on Rex Ryan's staff for the past four seasons. Despite the Jets' struggles in 2012, Pettine's unit only allowed 189.8 passing yards per game, which was second best in the NFL.
"First and foremost was the opportunity to work with a quality coach like (Bills coach) Doug Marrone," Pettine said. "It was just a whirlwind for me when the opportunities came. When his name popped up people came out of the woodwork to recommend him. He's pure football. The biggest thing for me is also to coach in an area with passionate fans. I grew up a coach's son and in a community where it was all about football. It's great to be somewhere where the fans are so passionate."
The Bills need defensive help as they finished 22nd in total defense in the NFL this past season. Marrone said he's looking forward to Pettine's aggressive approach on the defensive side of the ball.
"His defenses are known for their relentless attacking style," Marrone said. "They can be very difficult for offenses and create all kinds of mismatches. When I accepted the job, that's exactly how I envisioned our defense and so Mike was the coach I felt was best suited to lead our defense."