Tom Brady aside, NFL playoffs defined by defense

Aaron Rodgers played spectacularly against the Falcons on Saturday, delivering easily the best quarterback performance of the playoffs so far. It was about time that a quarterback matched the work of the defenses, which have taken over this postseason. Even Rodgers' accomplishment had to share credit with his defense, which turned the game in the Packers' favor, as it has all season long.

In a league that allegedly belongs to quarterbacks, this portion of the season has been claimed, somewhat ruthlessly, by Troy Polamalu, Ed Reed, James Harrison, Terrell Suggs, Clay Matthews, Darrelle Revis, Julius Peppers, Tramon Williams ... an assortment of safeties, corners, linebackers and defensive ends who define most of the teams left standing.

The must-see game of the weekend was the Bruiser Bowl between the Steelers and Ravens, in which Ben Roethlisberger proved himself worthy of sharing a locker room with Polamalu and Harrison. There will be no comparable showdown between great quarterbacks in the divisional round. Except for Tom Brady and Rodgers, most of them had been sent home for the winter.

As the 49ers prepare for the future, they might want to emphasize pushing the defense toward excellence, and setting the immediate offensive goal at competence rather than dominance. A year ago, that idea would have seemed counterculture, defying not only the 49ers' history, but also the critical results from 2009. Brett Favre, Peyton Manning and Drew Brees all took their teams to the conference finals, and Manning reached the Super Bowl with a negligible running game for support.

Offenses, and quarterbacks in particular, really did rule. The offensive leaders of 2009 in the NFL went further in the playoffs than the defensive leaders, with the top offensive team (the Saints) winning the Super Bowl. This year, only two of the top five offensive teams (Eagles and Colts) made the playoffs, and both exited the first weekend. Four of the top five defensive teams made the playoffs, and three of them (Jets, Steelers, Packers) have already won at least one playoff game.

More than anything else, pro football is a game of adaptation. As pass-rushing evolved, the left tackle grew in importance. As blitzes increased, quicker drops evolved. So the league of quarterbacks was bound to give way, pretty quickly, to a league full of defenses that could flummox them.

The eight teams that went into this weekend's divisional round included a heavy concentration of highly touted young quarterbacks - six first-round draft picks under the age of 29. But the Jets and Bears, with the unsteady Mark Sanchez and deeply unreliably Jay Cutler under center, would be nowhere without their defenses.

Rodgers has validated his place among elite quarterbacks over the past two weekends, but in both playoff wins, he benefited from playing against a mediocre defense while his own defense shuttered the opposition. The Packers still have a very questionable running game, which flourished against the Eagles last weekend because Philadelphia had allowed its defense to decay terribly.

No matter how much electricity Michael Vick and DeSean Jackson brought to the Eagles' offense this season, the deficiencies on the other side of the ball promised to derail the team's push for a sixth trip to the NFC title game in the last decade. Even their exhilarating 38-31 comeback against the Giants could not help but mark the Eagles as fraudulent. The Packers gave up 31 points just once all season - to the Patriots. The Steelers can make the same claim; they let the Patriots run over them 39-26.

The Pats are the aberrant playoff survivor. They look to their quarterback first, last and almost always. Their defense is ranked 25th in the NFL in yardage allowed, but first in interceptions - possibly because Brady's offense puts opponents far behind so quickly that they have to spend most of the game forcing throws. His 335 consecutive pass attempts without an interception make him seem almost untouchable, and so opponents have resorted to verbal shots.

Jets cornerback Antonio Cromartie, in keeping with his team's open-mouth policy, used an obscene term to describe the Patriots' quarterback this week, and in Baltimore, Suggs - who probably should have been more concerned about the Steelers - called Brady's three Super Bowl wins tainted. Suggs cited the "tuck rule" playoff win in 2002 and the Patriots' repeated videotaping of other teams' defensive signals.

But Brady became even more lethal after the videotaping was discovered and penalized in 2007. That was the season that the Patriots veered away from dissecting teams with a relentless defense, and began demolishing them offensively. The shift has yielded some amazing games, and an undefeated 2007 regular season, but no championships. If he can't win it all this year, he'll be tainted in a fairly common fashion - as a quarterback who needs a dominant defense.

E-mail Gwen Knapp at gknapp@sfchronicle.com.

This article appeared on page B - 1 of the San Francisco Chronicle