Want to shock and amaze your friends? Monday morning at work, ask someone to pick up the sports page and flip to the football box scores. Tell them to give you the number of yards gained passing and the number of throws. Then divide the first stat by the second. Without knowing who played, where they played, how many yards they rushed for, etc., you’ll be able to tell them who won four out of five times. Try it, it works.

The NFL passer rating is needlessly complicated and results in a number that is incomprehensible. But Pass Efficiency Rating, or PER, is simple, easy to calculate, and easy to understand. To figure PER, just take the number of yards a passer throws for, subtract 50 yards for each interception, and divide by the number of throws.

The result can be called “adjusted yards per pass,” and what it tells is that Drew Brees, Kurt Warner, and David Carr are having better seasons than the NFL thinks; that Tom Brady, Brett Favre, and Michael Vick aren’t as good as the NFL thinks, and that Peyton Manning is better than any of us realize.

In 1990, I did a study with Steve Sabol of NFL Films to determine the most important basic statistic in pro football. What, we wanted to know, was the single best indicator of power in the pros? What was football’s equivalent of on-base average? Or, stated another way, what was the one stat that best correlates with winning in the NFL?

Sifting through thirty years of NFL stats, we realized that the most important single stat in pro football is yards per throw. From 1960 through 1989, the team that averaged the highest number of yards per throw in an NFL game won 83% of the time. The last time I calculated the stat for every NFL game, after the 1996 season, the win percentage was slightly over 82%.

The second most important statistic that correlates best with winning and losing is interception percentage. Stated simply, the best offenses tend to throw fewer interceptions and the best defenses tend to get more. The question, then, is how to combine yards per pass with interceptions into one handy, easily usable number.

W.W. “Pudge” Heffelfinger, Walter Camp’s first All-America football player in 1892 and the first man to sign a pro football contract, observed football until his death in 1954 and judged the value of an interception to be about 50 yards. Pudge was very astute. In 1990, we added up all the yards gained in all NFL possessions and all the yards from every punt, then averaged them out. We arrived at the same conclusion as Pudge: a team loses, on average, about 50 yards worth of real estate every time it throws an interception.

I’ve been trumpeting the significance of yards per pass and interception percentage since the publication of my book, Football By The Numbers 1987, but I still can’t get anyone to listen. Most football stats in USA Today or in the record books don’t even include yards per pass as a category. You never hear a TV commentator talk about it.

The NFL’s passer rating system does include it as an important stat in the calculation, but doesn’t give it enough weight. That’s the basic problem with the NFL system: It accords the same value to a vital stat like yards per throw as it does to relatively unimportant ones, like pass completion percentage. (You don’t have to be a statistician to understand how little pass completion percentage means. Just ask yourself if you would rather complete three of three passes for nine yards or one of three passes for 10.)

A criticism of PER is that it can’t account for what a quarterback on a bad team might do with better blockers and receivers. That’s true – but PER is actually fairer than any other system. For instance, Kurt Warner is penalized under the NFL system for having thrown only six touchdown passes in 277 throws. But good quarterbacks on bad teams don’t get very many opportunities to throw TD passes.

Warner has actually been pretty effective this year, much more effective, for instance, than the much more celebrated Tom Brady and Brett Favre, and by virtue of his respectable yards per pass average and his miniscule interception rate (just 1.4% of his passes have been intercepted, the lowest rate of anyone in the league with over 250 throws) he deserves his seventh-place rating.

Conversely, the NFL overrates Tampa Bay’s Brian Griese for his gaudy but unimportant pass completion percentage of 69.3%, second highest in the league this year. Griese’s interception rate of 3.6% places him 22nd in the league.

Regarding Peyton Manning, it ought to be said that too much attention has been paid this season to his pursuit of Dan Marino’s record for single season touchdown passes. The amazing thing about Manning is not so much his productivity as his incredible efficiency.

Only a handful of passers since 1960 have averaged over nine yards per throw during a season, the equivalent of a baseball player hitting over .350. Manning’s yards per pass after 14 games, 9.24, would be roughly the equivalent of a ballplayer hitting around .380,with 9.5 being .400.If Manning’s numbers were translated into batting stats in baseball, he’d be Barry Bonds with the steroid rumors.

By either method, PER or the NFL’s, Michael Vick is vastly overrated (Vick’s PER is 5.34, 21st in the league, and his NFL rating, 76.6 is 26th.) Vick, of course, is a superb runner, but in the NFL, passing is king. If pro football statistics were properly understood, nobody would be awarding Michael Vick a ten-year contract.

Vick certainly has enormous potential – some have gone as far to say he has the most potential of any quarterback since Joe Namath. Maybe, but this is Vick’s fourth NFL season, and by the end of Namath’s fourth NFL season, people weren’t talking about his potential, but his accomplishments. Right now, PER indicates that surrounded by the same personnel, you’d win more games with Kurt Warner than you would with Michael Vick.