The most important stat in football

It's official, sports fans: Passer Rating Differential is the most important stat in football. It's the one indicator virtually guaranteed to separate winners from losers and champs from chumps.

If your team dominates this indicator, it dominates on the field. If your team's bad in this indicator, it's bad on the field.

Just ask the 2010 Super Bowl champion Packers, who finished the year No. 1 in Passer Rating Differential (+31.7), or the dismal 2010 Panthers, who finished the year with the league's worst record (2-14) and worst Passer Rating Differential (-24.0).

Put most simply, wins and losses move in lock step with Passer Rating Differential (PRD), a Cold, Hard Football Facts "Quality Stat" because it has a direct correlation to success. In this case, the correlation is shocking even to the folks who created the stat.

How good is the stat? Consider that 40 of 71 NFL champs since 1940 (56 percent) finished No. 1 or No. 2 in Passer Rating Differential.

History Of Passer Rating Differential

We have long known that success in the NFL is all about highly efficient passing attacks -- and it always has been, dating to the dawn of the T-formation in the 1940s. The best offenses are those that pass the ball most effectively, as measured by passer rating. The best defenses are those that shut down opposing quarterbacks most effectively, as measured by what we call Defensive Passer Rating. The best teams are those that do both most effectively.

To prove the importance of passing efficiency, we introduced Passer Rating Differential before the 2009 season. It simply subtracts what we call a team's Defensive Passer Rating (the passer rating of a team's opponents) from its Offensive Passer Rating. It's been a runaway success, beyond even when we imagined.

New Orleans finished No. 1 in Passer Rating Differential in 2009, the first year of the indicator's existence. That year, the Saints won the Super Bowl. Green Bay finished No. 1 in Passer Rating Differential in 2010, and they, too, won the Super Bowl. That made us two for two picking Super Bowl winners simply by looking at the Passer Rating Differential charts.

But we needed to know more to prove this was no fluke. And, folks, it's no fluke.

During the 2010 postseason, we looked at the Passer Rating Differential of every single NFL champion since 1940, the year that saw the very beginnings of the modern quarterback position and modern passing game.

It was a treasure trove of data: the average NFL champion over the past 70 years produced a truly incredible Passer Rating Differential of +27.4 (82.3 Offensive Passer Rating vs. 54.9 Defensive Passer Rating). That's dominance in the passing game.

Our most recent round of analysis goes one step further than just looking at the champs. With a big assist from Cold, Hard Football Facts analyst, statistician and spreadsheet savant Luis DeLoureiro, we compiled the Passer Rating Differential of every team since 1940.

The findings give us an incredible cache of amazing data that we'll roll out throughout the 2011 season, all of it proving that Passer Rating Differential moves in lock step with wins and losses,

The Passer Rating Differential Top 25

Below is a list of the Top 25 teams in Passer Rating Differential since 1960. We decided to go with 1960 because it's a watershed year in NFL history, with the advent of the AFL. But we also began at 1960 because many teams at the very top of the all-time Passer Rating Differential list, and almost every team at the bottom, were from the 1940s and 1950s.

The top three teams all time in PRD, for example, are the 1943 Bears (+73.3), 1941 Bears (+65.0) and 1942 Bears (+60.0). The worst teams all time in PRD all played in the 1940s, as well. At the bottom of the list is the 1945 Steelers (-70.2).

The disparity in PRD in the 1940s stood out as a clear statistical anomaly and spoke to many issues with football in that era: namely, a disparity in modernization -- some teams used the new T formation, Chicago most notably, and others didn't. There was also a disparity in talent, one that was aggravated by the roster depletions caused by World War II. The 1950s also produced a pretty noticeable disparity from top to bottom, though not as distinct as in the 1940s.

Here are some of our immediate reactions to this list: