Defense wins championships in the NFL -- except when teams known for offense enjoy Super Bowl success.
Home-field advantage is everything in the playoffs -- except when a wild-card team wins it all.
Teams geared to run the ball and stop the run win in the playoffs -- except when passing teams emerge with the Lombardi Trophy.
Super Bowl teams tend to have established franchise quarterbacks -- except when they employ journeymen.
Even the most time-honored playoff mantras aren't immune to exceptions. Some hold up to scrutiny better than others. Some are outdated. Some are outright myths. At the least, the game has changed enough over the years to warrant revisiting them.
ESPN.com analyzed every team in every season from 2000 to 2007 to see how strengths and weaknesses translated to playoff performance. A goal was to project which teams might enjoy playoff success based upon characteristics evident during the regular season.
To that end, we measured each of the 254 teams during 2000-07 in 36 statistical categories tracked by the league (18 on each side of the ball). Statistical analysis revealed which categories correlated most strongly to regular-season victory totals. We then noted how many playoff games pre-2007 teams won, and which teams won and lost Super Bowls.
Alas, no single factor determines whether teams win playoff games and Super Bowls. Some simply tend to be more important than others.
1. Conventional wisdom: Defense wins championships.
Scoring defense is far more important than yardage-related indicators.
The 30 teams that allowed the fewest regular-season points since 2000 won 38 playoff games and appeared in eight Super Bowls, winning five. None of the 35 remaining statistical categories, including point-differential per game, produced such telling results.
Since 2000, only the 2006 Indianapolis Colts won a Super Bowl after allowing more than 17 points per game during the regular season. They allowed 22.5, but their defense improved once safety Bob Sanders hit his stride late in the season. The Baltimore Ravens and
combined for one offensive touchdown in postseason losses to the Colts.
The Colts allowed only 16.4 points per game this season, fewest in the league.
The Pittsburgh Steelers (16.8) and Tampa Bay Buccaneers (16.9) also held teams below 17 per game. The New England Patriots (17.1) were close behind. But New England, like the Colts last season, built its reputation on offense.
"Some guys are going to gasp and put their hands to their mouth, but defense is more important than offense," former Buffalo Bills coach and general manager Marv Levy said.
"Don't apply for a job and tell that to the owner. The owner will say you are playing not to lose.
"Good defense keeps the other guy out of the end zone, yes," Levy said, "but you also give your own offense a chance to fail without getting into dire straits. And when you've got defense, you're getting takeaways, and man, does that make a difference in where you take over the ball and your opportunity to score after that."
Proclaiming that defense wins championships doesn't diminish the importance of other aspects of the game. Offensive categories have become more strongly correlated with victories over the past two seasons, particularly with Tom Brady and the Patriots' posting a 16-0 record this year.
2. Conventional wisdom: Home-field advantage means everything.
Road teams won three-fourths of wild-card playoff games following the 2004 and 2005 seasons. Two years ago, the Steelers kept winning on the road right through Super Bowl XL in Detroit, where a decidedly pro-Pittsburgh crowd cheered them to victory over Seattle.
Baltimore won two road playoff games before beating the New York Giants in the Super Bowl following the 2000 season. The next year, eventual champion New England won the AFC title game in Pittsburgh. A year after that, eventual champ Tampa Bay won the NFC title game in Philadelphia.
Home teams have won 20 of 28 divisional-round games since 2000. But one home team lost in the conference championship round for six consecutive seasons until Chicago and Indianapolis won at home last season.
3. Conventional wisdom: Teams must run the ball and stop the run.
Running the ball and stopping the opponent's run is always a good idea. For unknown reasons, teams that have done so most convincingly haven't gone very far.
Fifteen teams since 2000 have rushed for more than 140 yards per game while holding opponents below 100 yards per game. Of them, the 2005 Seahawks were the only one to win more than one playoff game. The others -- including non-playoff teams like the current Minnesota Vikings -- combined to win five.
Thirty teams since 2000 have outrushed their opponents by at least 40 yards per game (not counting the Vikings,
Jacksonville Jaguars and the Steelers this season).
Those teams won 22 playoff games and went 2-2 in Super Bowls (two of those teams -- Pittsburgh and Seattle -- played one another in Super Bowl XL). That's not bad, but numerous competing indicators produced similar results. The 30 highest-scoring teams over the same period won 23 playoff games, including two of six Super Bowls, for example.
Possessing the NFL rushing champion doesn't mean much come playoff time, either. The past seven Super Bowl champions were led in rushing by players who ranked 18th on average among the NFL leaders.
No NFL rushing champ since Denver's Terrell Davis in 1998 has won a Super Bowl in the same season. Back-to-back rushing titlist LaDainian Tomlinson will try to break the streak this season, but his San Diego Chargers haven't won a playoff game in more than a decade.
Five teams since 2000 gained more yards rushing than passing during the season. Three won at least 10 regular-season games, but only the 2004 Atlanta Falcons won a playoff game, and they were one-and-done.
4. Conventional wisdom: Balanced offenses always have an advantage.
Truly balanced teams generally aren't very proficient through the air. But even teams with highly productive passing and running games have struggled to win in the playoffs.
The Philadelphia Eagles were the only team this season to average more than 230 yards passing and 120 yards rushing per game. They finished 8-8.
Fifteen other teams have hit those averages since 2000. Eight finished the regular season with double-digit victories, but together these 15 teams won only five playoff games. Of the group, only the 2001 St. Louis Rams reached a Super Bowl, and they lost.
The least balanced offenses haven't fared much better. The current season produced five of the 17 largest pass-rush yardage imbalances since 2000. The 2000 Rams were least balanced, followed by the 2005 Arizona Cardinals, current Patriots and current New Orleans Saints.
The other 12 least-balanced teams went 0-2 in Super Bowls while winning nine playoff games.
5. Conventional wisdom: Super Bowl teams usually have franchise QBs.
Plenty of teams have won championships with caretaker quarterbacks, but not so much lately. Brady, Pittsburgh's Ben Roethlisberger and the Colts' Peyton Manning have won five of seven Super Bowls this decade, though Roethlisberger struggled.
6. Conventional wisdom: Momentum is crucial heading into the playoffs.
Verdict: TRUE or FALSE
Home playoff teams have enjoyed their most success in the divisional round, after having a bye week to rest. The time off presumably would hurt a team's momentum, but not enough to offset the apparent advantage of extra time.
The best teams tend to win no matter the time of year. Recent Super Bowl winners often finished the regular season strong.
The 2000 Ravens won their final seven. The 2001 Patriots won their final six. The 2003 Patriots won 12 in a row following a 2-2 start. New England won eight of its final nine a year later. The 2005 Steelers won their final four after a three-game losing streak, outscoring opponents 115-33.
Two teams have won Super Bowls since 2000 without finishing strong. The 2002 Bucs lost in Weeks 13 and 16. The 2006 Colts lost four of their final seven.
7. Conventional wisdom: Anything can happen in the playoffs.
The Steelers won a Super Bowl as the AFC's sixth seed two years ago, defeating top-seeded Seattle. In 2003, Carolina parlayed a wild-card victory into a divisional-round upset over a 12-win Rams team averaging nearly 28 points per game.
The 2001 Patriots were anything but a dynasty when they shocked the heavily favored Rams in the Super Bowl. Those Rams, considered close to invincible coming off a 14-2 season, resemble the current Patriots far more closely than any team this decade.
Of the 254 teams that have played during 2000-07, the current Patriots are No. 1, with an average ranking of 11.6 across the 10 categories that correlate most strongly to total victories. The 2001 Rams ranked 12.9 on average. None of the remaining 252 teams averaged higher than 32.8.
The 2001 Patriots ranked 116.6 on average in these categories (point differential per game, points scored per game, points allowed per game, yardage differential per game, yards per pass attempt, time of possession, yards per game, yards per play, first downs per game and passing yards allowed per attempt).
8. Conventional wisdom: Special teams are one-third of the game.
Chicago's Devin Hester returned the opening kickoff for a touchdown in Super Bowl XLI, only to watch Indianapolis blow out his team from there. The 1972 Redskins blocked a kick in the Super Bowl, but Miami won the game. We remember Buffalo's last-second Super Bowl miss against the Giants because it was dramatic -- and unusual.
The 15 highest-ranked special-teams units from 2002 to 2006, as defined by the Dallas Morning News' well-regarded point system, won anywhere from two to 13 regular-season games.
Five of the top 23 appeared in Super Bowls, and special teams certainly played a role.
But offense and defense matter more from play to play. There's a reason specialists are among the lowest-paid players in the game.
Teams exceptionally strong in specific areas can sometimes win championships in spite of shortcomings that might derail others.
Defensive dominance carried the 2000 Ravens. New England's passing game has been prolific enough this season to make potential flaws appear imaginary.
The Patriots' previous Super Bowl winners ranked among the very best teams of the decade in forcing opponents to settle for field goals, and they were not alone. Teams that ranked among the top 30 since 2000 in red-zone defense have gone 5-1 in Super Bowls.
But the proliferation of offense in the last two seasons is changing things. The Colts won it all last season despite ranking 215th this decade in red-zone defense. The current Patriots rank 212th.
Defense has won its share of championships, no doubt, but the Patriots haven't had to bother with such details while scoring nearly 37 points per game.
No team since 2000, save for the 2001 Rams, has approached their level of dominance. Those Rams lost in the playoffs only when faced with a New England defense that allowed only 17 points per game during the regular season. The Patriots won that Super Bowl, 20-17.
Very few current teams fit into the same class defensively. The Colts, Steelers and Bucs come closest. Each allowed fewer than 17 points per game during the season. Green Bay (18.2) was better than Dallas (20.3) among teams that also fared well in the 10 categories correlated to winning, but the conversation keeps coming back to Indianapolis.
The Colts finished this season ranked third among all teams since 2000 in the 10 categories most strongly correlated to winning. Dallas ranked 12th, Green Bay 20th -- highest among current NFC teams.
But these Colts also led the league in scoring defense. That gives them an edge.
The bottom line: The NFC might have little to say about which team is best this season.
Bring on the Colts and Patriots.
Mike Sando covers the NFL for ESPN.com.