Conference Championships: Numbers Crunching

This week, Football Outsiders takes a look at Sunday's AFC and NFC championship games and applies statistical analysis gathered during the regular season. Much of the analysis is based on DVOA (Defense-adjusted Value Over Average), which takes every play during the season and compares it to the league average based on situation and opponent. DVOA and Football Outsiders' other advanced stats are explained here.

Chargers at Patriots (Sunday), 3 p.m. ET

The New England Patriots and San Diego Chargers had the top two red-zone offenses in the league in the regular season, according to DVOA.

The Chargers also had the top defense in the red zone, which was astounding, considering they had the worst red-zone defense in 2006. In addition, the Chargers had the best defense in the next 20-yard area, when their opponent was between the 21- and 40-yard lines. New England's offense ranked fourth in this area. The Indianapolis Colts, whom the Chargers beat last Sunday, had the best offense in this area.

The Chargers ranked seventh in DVOA against No. 1 receivers and first against No. 2 receivers, but 30th against other (i.e., slot) receivers. The San Diego pass defense dramatically improved at midseason against the starting receivers, but only slightly against other receivers. This is not a good weakness to have against Wes Welker.

They might be known for their great stable of running backs, but the Chargers gained an average of just 4.7 yards on first down -- only the Chicago Bears, Kansas City Chiefs and San Francisco 49ers were worse. The Patriots allowed a league-average 5.4 yards per first down.

Of course, if there aren't a lot of yards gained on first down, you end up with second-and-long. In that situation, the Chargers' offense was good (ninth in DVOA), while the Patriots' defense had problems (20th in DVOA). The Chargers gained an average of 8.7 yards when throwing the ball on second-and-10 (or more), more than any other offense.

The Patriots led the league in offensive Adjusted Line Yards, while the Chargers were 29th on defense. However, San Diego's run defense improved significantly over the second half of the season. Through Week 9, the week in which the Chargers gave up the NFL single-game rushing record to Adrian Peterson, their defense ranked 30th in ALY. From Week 10 on, they ranked 20th.

Usually, one of the strengths of the 3-4 defense is the ability to hide your pass-rushers -- the opponent never knows which linebacker or linebackers are coming, and that's before we include the possibility of zone blitzes. But the Chargers don't use their 3-4 this way. In general, opponents know who is coming: outside linebackers Shawne Merriman and Shaun Phillips. The Chargers rush five more often than any other defense, but rush six or more less often than any team except Indianapolis.

Through Week 15, our charters marked only seven plays on which either Merriman or Phillips was the defender in coverage, compared to 45 plays with either Matt Wilhelm or Stephen Cooper in coverage. Coverage responsibilities for 3-4 defenses like the Pittsburgh Steelers' or New England's were much more evenly distributed among both inside and outside linebackers.

Both special teams are strong, although the Chargers are superior on both punts (with Mike Scifres) and punt returns (with Darren Sproles). It's also worth noting that while these teams ranked second and third in net kickoff value, they did it in different ways. The Patriots have Stephen Gostkowski, one of the top two or three kickoff men in the league, and good coverage. Nate Kaeding was average on kickoffs this year, but the Chargers had exceptional kickoff coverage.

• More Chargers-Patriots: Intel Report | EA Simulation | Preview

Giants at Packers (Sunday), 6:30 p.m. ET

According to Adjusted Sack Rate, the Green Bay Packers had the best offense in terms of avoiding sacks, while the New York Giants had the best pass rush.

We can attribute the upswing in the Packers' rushing performance almost entirely to Ryan Grant. After Week 6, when Grant became a factor, the Packers' average yards per carry by running backs improved from 3.57 to 4.90, but their Adjusted Line Yards (which filters out longer runs in an attempt to better measure the offensive line) only improved from 3.58 to 4.12.

The Packers did not blitz very often. According to our game-charting numbers, only three defenses were less likely to send more than four pass-rushers. The Packers might want to try blitzing a little more in this game. During the regular season, Eli Manning struggled more when the defense big-blitzed, averaging a yard per play less. Big-blitzing Manning was an important part of the Minnesota Vikings' game plan when they whipped the Giants 41-17 in Week 12, and the Washington Redskins also used it to beat the Giants in Week 15.

Don't be surprised if the Giants can't stuff it in to the end zone with Brandon Jacobs once they get down near the goal line. The Packers ranked third in defensive DVOA against the run in the red zone.

The Giants had a poor defense in the red zone: 23rd against the pass, 30th against the run. This is one thing that has not changed during their three-week string of strong games. New England, the Tampa Bay Buccaneers and the Dallas Cowboys got past the Giants' 18-yard line eight times. Seven of those drives ended in touchdowns. The only one that didn't was the first Dallas drive of the third quarter last Sunday, which ended in a field goal.

Another trend that has not changed, even with the Giants playing well over the past three weeks: Their defense doesn't start the game well. During the regular season, the Giants ranked 29th in defensive DVOA in the first quarter. They gave up a touchdown drive in the first quarter in each of the past three games, although the actual touchdowns were the first play of the second quarter against New England and Dallas.

The Packers were slightly above average on special teams, the Giants slightly below. However, each team's strengths match up, as do their weaknesses. The Packers were strong on kickoffs and punt returns, weak on punts and kick returns. The Giants were strong on kick returns and punts, weak on punt returns and kickoffs.

• More Giants-Packers: Intel Report | EA Simulation

Aaron Schatz is president of Football Outsiders Inc. and the lead author of Pro Football Prospectus 2007 and 2008.

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