Only three of the top 10 sack teams from the 2009 regular season remain in the playoffs. And just four of the 10 franchises that surrendered the fewest sacks in '09 are still in contention for a Super Bowl XLIV berth.
But combine those two critical disciplines -- the ability to knock down the other guy's quarterback and to keep your own passer perpendicular -- and the list of playoff survivors that have advanced to the weekend's division-round games grows considerably.
Six of the eight division-round clubs were among the NFL's top 10 in sack differential -- the number of sacks recorded by a team's defense minus the sacks that its offense allowed -- during the regular season. That includes all four of the top sack-differential leaders. In order, they were Indianapolis (plus-21), Arizona (plus-16), New Orleans (plus-15) and Minnesota (plus-14).
Seven of the eight clubs that are still playing, with Baltimore (minus-4) being the lone exception, recorded a positive sack differential during the season.
For obvious reasons, the top-seeded Colts led the way. There were 15 teams that registered more sacks than Indianapolis' total of 34, which was slightly below the league average. But the protection-diligent Colts surrendered a league-low 13 sacks, including just 10 against NFL Most Valuable Player Peyton Manning, who was dumped only once for every 58.1 dropbacks.
Speaking this week of his team's recent shortcomings in sacking the opposition quarterback (just 61 sacks the past two seasons), New England coach Bill Belichick noted to the Boston-area media: "There's really nothing more important than the pass rush."
That sentiment may have traction among league coaches, especially this year. And since 2002, when the NFL realigned into eight divisions, teams that won division-round games averaged 21.6 points, suggesting that a potent passing attack is paramount. But in a season when offenses in the NFL skewed heavily toward the passing game, it is actually the combination of sacks recorded and surrendered that might be more critical.
Five of the top 10 teams in passing offense are still in the playoffs, and the postseason survivors include two clubs from the top 10 pass defenses. But registering sacks, and also avoiding them, might be even more critical to a club's success. A team's sack differential quotient is inarguably an esoteric statistic, but there is no denying its relevance.
"From both [the offensive and defensive] standpoints, the sack is a difference-maker," said Baltimore linebacker Terrell Suggs, who has averaged 8.2 sacks per season in his seven-year career and has five sacks in the Ravens' past four postseason contests. "For a defense, the sack generates a lot of excitement and momentum, almost like a dunk in basketball. For the offense, it can be deflating on the field, and psychologically, too."
Suggs had a sack, strip and fumble recovery against New England's Tom Brady in the first quarter last week, and that trifecta led to a touchdown that boosted the Ravens into an early 14-0 lead.
Each of the teams that was victorious in the wild-card round sported a positive sack differential in its respective game. Dallas was a plus-2, Baltimore and the New York Jets were both plus-3 and Arizona was plus-4.
The last of Arizona's five sacks of Green Bay quarterback Aaron Rodgers, on a hit by defensive back Michael Adams, led to linebacker Karlos Dansby's fumble recovery and winning touchdown return in overtime. Meanwhile, Arizona quarterback Kurt Warner, who had more touchdown passes (five) than incomplete passes (four) in the win, was sacked only one time.
Since 2002, the 28 winning teams in the division round own a 57-47 edge in sack differential, and only seven clubs that didn't win the sack battle were victorious.
The last seven Super Bowl-winning teams had positive sack differential totals in their regular seasons. Among the past 10 Super Bowl winners, only Pittsburgh in Super Bowl XLIII posted a negative sack differential (minus-1) in the title game.
"To be successful," said Jets coach Rex Ryan, whose team had a plus-2 sack differential in the regular season, "you've got to hit the quarterback and be disruptive."
Apparently, though, that's only half the equation.
Len Pasquarelli is a senior writer for ESPN.com.