It is often said that defense wins championships, but a look at this year’s 12 NFL playoff teams would seem to indicate that defense doesn’t necessarily even get you into the postseason. A number of teams built around defense failed to even post winning records in 2004, including Chicago, Miami, Washington, and Tampa Bay. The average playoff team this season ranked eighth in the league in yards gained, but only 16th in yards allowed.

A look at the Football Outsiders’ Defense-adjusted Value Over Average ratings (DVOA), which break down each play of the season and compare it to the NFL average based on situation and opponent, makes the offensive inclination of this year’s playoff teams even clearer. Only one of the top 10 offenses, second-ranked Kansas City, missed the playoffs. But seven of the top 10 defenses missed the playoffs, including the top three: Buffalo, Baltimore, and Washington. Among playoff teams, only Pittsburgh, New England, and Denver had defenses in the top 10, according to our play-byplay analysis.

Scoring around the league was up in 2004, thanks mostly to the new emphasis on illegal contact rules, which led to looser pass coverage by defensive backs. To be sure, this doesn’t explain why so few strong defensive teams made this year’s playoffs – for a variety of unrelated reasons, teams like the Redskins and Bears were sunk by major quarterback problems. But this year’s slant toward offense has allowed high-scoring teams like Philadelphia and Indianapolis to hold out hope that they can defy the rule that defense wins championships.

Except there’s no need to defy this rule: It’s not true in the first place.

Fans may be forgiven for finding this difficult to believe. The idea that defense is more important in the postseason is repeated ad nauseum by NFL analysts once the calendar has turned to January. Recent history also seems to support the concept: Of the past four Super Bowl champions, only the 2001 Patriots did not lead the NFL in fewest points allowed.

But this trend toward defense-oriented champions was preceded by a trend towards offense-oriented champions. From 1991 through 1999, every Super Bowl champion ranked either first or second in points scored during the regular season, except for the 1995 Cowboys, who ranked third.

Since the liberalization of passing rules in 1978 (and excluding the strange 1982 strike year), a total of 16 Super Bowl winners finished in the top five in points scored during the regular season, and a total of 18 Super Bowl winners finished in the top five in points allowed during the regular season.

Those fairly even numbers are a good indicator that neither superior offense nor stifling defense has an advantage when it comes to winning the Super Bowl: What matters is balance.

Most Super Bowl champions have ranked among the league’s best teams in both offense and defense. In recent years, the difficulty of amassing talent for both offense and defense under salary cap restrictions have made that kind of dominance less frequent in recent years, but teams that are far better in one area than the other still have a very hard time winning the Super Bowl.

Since 1999, the first year for which we have broken down play-by-play data to provide DVOA statistics, no team has made it to the Super Bowl with one unit ranked in the NFL’s top 10 in DVOA and the other unit ranked in the bottom 10. The only one that came close was the 2000 Baltimore Ravens, ranked by DVOA as first in defense but only 20th in offense.

That could change this year, though not necessarily because of the league-wide emphasis on offense. After all, there have been other seasons where offensive numbers were as high as 2004, and teams with strong offenses and poor defenses didn’t fare any better than usual in those years. But given this year’s diluted NFC playoff pool, the conference may end up represented by a team with a strong offense and a terrible defense simply because those were the teams that made the playoffs.

Of the six NFC contenders, only Atlanta and Philadelphia have defenses that rank in the top half of the league. The defensive units fielded by St. Louis, Green Bay, and Minnesota rank 29th, 30th, and 31st, respectively. If one of these teams actually does advance to the Super Bowl, the odds of it beating a more balanced AFC opponent are tiny.

As for the Colts, play-by-play analysis shows that they are more balanced team than their reputation would suggest. According to official NFL yardage stats, the Colts are ranked second in offense and 29th in defense; DVOA puts the offense where it belongs, ranked first, and the defense moves up to 18th.That’s high enough to believe that the Colts have a reasonable shot at the title.

In the end, though, the AFC champion will likely be one of two supremely balanced squads: Pittsburgh (seventh in offense, fourth in defense) or New England (fourth in offense, sixth in defense). When one of these teams wins Super Bowl XXXIX, you can expect to hear the usual canard about defenses winning championships. Of course, the winner will have depended equally on its highly rated offense. Either offense or defense can bring home a title, but it is best to have both.

Mr. Schatz is the editor in chief of FootballOutsiders.com.