Behind the numbers: Defense, fancy QB footwork

Doug Farrar
Yahoo! Sports

Each NFL team found different ways to reach the conference championship, but for the four remaining contestants, the one common denominator was increased pass defense efficiency in the second half of the regular season.

All four teams – Pittsburgh Steelers, New York Jets, Chicago Bears and Green Bay Packers – rank in the top 10 of Football Outsiders' opponent-adjusted efficiency metrics in pass defense for the season's last eight weeks. Not all started the season that way:

Team Eff. rank (Weeks 1-9) Eff. rank (Weeks 10-17)
Green Bay Packers 3rd 1st
Steelers 4th 2nd
Bears 13th 3rd
Jets 20th 6th

The Packers' pass defense, led by ridiculous Pro Bowl snub Tramon Williams(notes), edged out the Steelers for the full season, and it's no surprise that these two teams are favored to make it to the Super Bowl.

The Jets have seen the biggest turnaround as Darrelle Revis(notes) rounded into shape and Antonio Cromartie(notes) played a bit better, though still not up to the expected standards. By those same pass defense metrics, the Jets finished 10th against No. 1 receivers (Revis' domain) and 24th against No. 2 receivers (Cromartie's responsibility).

The Bears mixed more aggressive coverage and better pass rush to increase their efficiency.

A closer look at the conference championship matchups:

Jets at Steelers

Steelers receiver Mike Wallace(notes) finished the regular season ranked second in average yards per reception with 20.95, behind only Philadelphia's DeSean Jackson(notes). But Wallace isn't the only Pittsburgh receiver who can grab the deep ball, which is why Ben Roethlisberger(notes) has an average pass length of 10.88 yards in the postseason. The difference between Big Ben and Kansas City's Matt Cassel(notes), who also averaged 10.88 yards per throw in his one postseason game? Cassel averaged just 3.33 yards per completion, while Roethlisberger comes out at 7.47 per actual catch this postseason. Of the four remaining quarterbacks, Roethlisberger's 4.42 yards after catch average is the lowest.

The Jets have seen a downturn in many of their pass defense stats with no consistent pass rusher and a secondary that is not what it was in 2009, but they allowed the NFL's lowest regular-season completion percentage (50.7). The problems came in their first downs (169) and touchdowns (24) allowed – both numbers put them closer to the league average. The Jets were near the bottom of the league in Football Outsiders' red-zone pass defense efficiency metrics (25th), and it will be hard for them to make it up on the offensive side. New York ranked 28th in red-zone passing offense, and the Steelers ranked third in that same defensive metric.

The Steelers ranked 29th in adjusted sack rate (sacks per pass attempt adjusted for down, distance and opponent), but that's to be blamed more on Roethlisberger than his offensive line. Whatever the reason, the Jets rank 11th in defensive adjusted sack rate and picked up 40 sacks, despite having a team leader (Bryan Thomas(notes)) with only six. Jets head coach Rex Ryan and Steelers defensive coordinator Dick LeBeau are perhaps the NFL's best when it comes to scheming pressure from different locations.

Packers at Bears

It doesn't take much evidence to confirm that Roethlisberger is one of the best quarterbacks on the run and under pressure, but he's got a way to go before he catches up with Green Bay's Aaron Rodgers(notes). In Football Outsiders' rushing efficiency metrics for quarterbacks, Rodgers finished first in 2009, and second to Michael Vick(notes) in 2010. He was the best quarterback when hurried in 2009, a trend that continued this season. Rodgers has seen a great deal of pressure, especially on his blind side. Left tackle Chad Clifton(notes) gave up 8.5 sacks this season, the most of his career, and Rodgers was sacked 31 times for 193 yards lost. Still, that's much better than the 50 takedowns for 306 yards he suffered in 2009. Rodgers was also hit 28 times in 2010, and Steelers linebacker James Harrison(notes) finished tied for third in the NFL with 14 quarterback hits in addition to his 10.5 sacks in the regular season and three in the playoffs.

Packers linebacker Clay Matthews'(notes) performance in the 2010 regular season transcended his sack totals/. He picked up 12 quarterback hits in addition to his 13.5 sacks. This could be the true battle of this game; two of the best teams in applying quarterback pressure, and two of the best quarterbacks in playing around it.

Rodgers has a 95.5 quarterback rating in the shotgun formation, and the Packers used the scheme 48 percent of the time, sixth-highest in the league. The Bears' defense saw more shotgun sets than any other (48 percent), but it was the NFL's second-most efficient team in defending against it. Jay Cutler(notes) has no relationship whatsoever with the shotgun; the Bears used the formation just 10 percent of the time, by far the league's lowest. The Packers were third-best defending against the shotgun, so no reason for Chicago to change now.