New Buffalo Bills coordinator Mike Pettine has small shoes to fill when it comes to creating an aggressive defense.

The Bills blitzed on just 15 percent of pass plays under Dave Wannstedt in 2012, according to News figures. Buffalo ranked last in the NFL in blitzing the quarterback, according to ESPN.

I know what you're saying: Tell me something I don't already know. Buffalo's lack of aggressiveness and the blandness of its pass rush were among the maddening aspects of the season for Bills fans.

Yet the degree to which they relied on a straight rush from four down linemen was amazing.

“Were they aggressive enough? Not even close,” said former Bills safety Mark Kelso, the team's radio color commentator. “I don't think they moved their defensive linemen enough or brought multiple rushes in a way that was effective. My philosophy has always been if you can't get there with four, you better rush five. If you can't get there with five, you better rush six. If you can't get there with six, you better rush three and drop eight.”

The Bills got a decent number of sacks — 36. That ranked 13th in the league in terms of sacks per pass attempt.

Overall, however, the amount of heat on the quarterback the Bills produced was insufficient. The proof is the Bills were terrible at getting off the field. They ranked 31st on third downs, allowing opponents to convert 44 percent in that situation. And it wasn't just because the run defense was bad. They were bad on third and long, too. On third and 6 to 10, they allowed foes to convert 45 percent of pass plays. That says the quarterback was too comfortable in the pocket and the Bills were too predictable.

“They don't move guys,” Kelso said, referring to the front four. “They started to twist and stunt a little more later in the year, but there was not nearly enough movement. Too many times guys would line up on the shoulder they're responsible for and that's the rush they'd take. Sometimes they'd execute a pass rush in that situation. But rarely did they go to the opposite shoulder, rarely did they extend the defense or slant.”

The Bills played too much zone defense, as well; not enough man-to-man coverage. Wannstedt repeatedly stated during the season that his defense was young. It was obvious he didn't trust his secondary to hold up if he devoted more men to the rush. His conservatism failed miserably.

In the season opener against the Jets, the Bills blitzed on just three pass plays, and their off coverage made it too easy for Jets quarterback Mark Sanchez. He completed 70 percent of his passes that day. For the full season, he hit only 54 percent, which ranked 30th in the NFL. The Bills blitzed Tennessee's Matt Hasselbeck just twice in the home loss to the Titans. That included no pressure on a fourth-and-9 touchdown pass from the Bills' 15 to win the game. They allowed St. Louis to march 84 yards in 14 plays to a winning touchdown in the final seconds. QB Sam Bradford wasn't blitzed on the drive.

There's plenty of blame to go around for the Bills' 6-10 season. But if Wannstedt had done a decent job, Chan Gailey still would be the head coach.

A word about blitzes. The above figures all refer to plays on which the defense rushes five or more men at the passer. It does not count four-man zone pressures, in which a lineman drops into coverage and a linebacker or defensive back joins the rush. The News numbers count all pass plays, plays in which the quarterback scrambled and plays wiped out by penalty. (So if a five-man rush resulted in a holding penalty or a pass interference, that counted.)

Heavy blitzing by no means guarantees success. San Francisco had the fourth fewest blitzes in 2011 and second fewest to Buffalo in 2012 but was a top-four defense both years. The Niners do a good amount of zone pressures, and they have a great edge-rush combination in Justin Smith and Aldon Smith.

However, seven of the top 10-ranked defensive teams in the league in 2011 rushed five or more on at least 29 percent of the pass plays, according to

The Bills had the fifth-lowest blitz rate (20.6 percent) under coordinator George Edwards in 2011. Their rate was 20 percent under Edwards in 2010, too, according to News figures. They were at 28 percent in 2009 and 32.6 percent in 2008 under Perry Fewell, again according to News figures.

While the Bills' four-man rush this year could have been better, it wasn't bad. The Bills got 28 sacks with a four man rush and just eight on blitzes.

In 2010, Buffalo had only 14 sacks with a four-man rush. In 2008, they had only six on a four-man rush but had 18 with blitzes. Fewell did a fine job of manufacturing pressure. Good thing Wannstedt wasn't coaching that season.

Bills Snaps

C.J. Spiller played 56.2 percent of the Bills' offensive snaps in 2012. Spiller averaged 35.6 offensive plays a game, and he played all 16 games.

Fred Jackson finished at 20.8 snaps a game over the 16 games, but he missed six games to injury. In the 10 games both Jackson and Spiller played together, Jackson averaged 33 snaps a game, while Spiller averaged 30.

Here were the play-time percentages for the Bills in 2012:

Offense: Andy Levitre 100 percent, Ryan Fitzpatrick 98.6, Stevie Johnson 93, Eric Wood 86, Cordy Glenn 80, Kraig Urbik 78, Scott Chandler 74, T.J. Graham 68.6, Donald Jones 66, C.J. Spiller 56.2, Chris Hairston 56.1, Fred Jackson 32.8, Brad Smith 31, Lee Smith 28.3, Sam Young 27.1, Chad Rinehart 16.3, Tashard Choice 12.3, Ruvell Martin 11.3, Corey McIntyre 10, Dorin Dickerson 9.7.

Defense: Stephon Gilmore 97, Jairus Byrd 93.9, Nick Barnett 92, Mario Williams 85.3, George Wilson 82.4, Kyle Williams 72.9, Marcell Dareus 72.4, Bryan Scott 54.3, Aaron Williams 50.4, Justin Rogers 49, Kelvin Sheppard 46.5, Kyle Moore 45, Nigel Bradham 36.2, Leodis McKelvin 31.7, Alex Carrington 31.4, Da'Norris Searcy 25, Spencer Johnson 22.7, Arthur Moats 11.

Injured players: Chris Kelsay finished at 26 percent. Over the first eight games, before he got hurt, he played 51 percent. Mark Anderson finished at 23 percent. Ron Brooks played 25 percent over the last nine games, once he was activated. Shawne Merriman played 31 percent once he joined the roster for the seventh game. Before he got hurt, tackle Erik Pears played 87 percent of the snaps.