If you're a football fan, or even if you have ever watched a football game on TV, then you know that the conventional wisdom is that a team has to have a good quarterback to win. That's why quarterbacks get paid more than any other player, and why the top five picks in the draft every year usually includes a pivot or two. If you were to look at the stats for week 15 in the NFL, though, you would wonder if this wisdom has any merit at all.

The week was marked by some impressively bad performances by winning quarterbacks. Brett Favre won against Detroit despite throwing three picks, none of which were due to bad luck or unfortunate tips. Vince Young didn't even cover the whole field once - he was 8-of-15 for 85 yards. Despite the fact that his team put up 40 points, the recently struggling Tom Brady only had 109 passing yards. Marc Bulger had 137. Philip Rivers' numbers were as bad as any - 8-of-23, 97 yards, no touchdowns, two interceptions.

It's not just that the players won with those bad numbers. They also all covered, and for the most part you didn't even have to sweat it if you bet on them. Tennessee and St. Louis were underdogs, and San Diego and New England faced multiple-score spreads, but only the Chargers looked like they weren't going to cover.

What has popped up several times throughout this season is that, despite the attention it gets, the passing game is not always the key to success. In week 15 the passer with the most yards in a game was 9-7 straight up, and only 7-9 ATS. The week before, the top passer went 8-7-1 ATS and 8-8 straight up. They were 8-7-1 ATS the week before that. We have this belief among sports fans and sports media that quarterbacking is crucial and all about glory, yet over the past three weeks, the top passer in games is only 23-23-2. In other words, if you were able to predict with perfect accuracy which team was going to have the better passing day over the last three weeks, you would have lost money. If you were to bet against those teams you would lose money, too.

If being the best passer in a game isn't a good way to cover a spread, then being the best passer on the entire week is clearly a kiss of death. Over the last nine weeks, the passer who piled up more yards than any other QB has won just once, and have only covered two times. Let me put that another way, because it is so bizarre that is seems almost impossible - the team that has put up more passing yards than any other team in a given week has lost eight of the last nine games.

A team can have a fluky passing performance, but surely teams with consistently strong passing games pay off at the betting window, don't they? Not so much. The top five passers in the league are Drew Brees, Peyton Manning, Marc Bulger, Jon Kitna and Carson Palmer. They are averaging a combined 272 yards per game, yet they are just 36-35-1 ATS. The top two teams against the spread, improbably, are Buffalo and Tennessee. J.P. Losman is ranked 17th in passing yards, and Vince Young is averaging only 150 yards passing in his 11 starts.

The current standard for passing excellence is Brees. The Saints' passing game is a finely tuned machine, and Brees has put up some sick numbers - 510 yards, 398, 384, 383. The thing is that his team has lost three of the four games he put those numbers up in. On the other hand, Brees has passed for less than 200 yards four times this year, and his team has won all four times. One likely reason for this, and for the shocking lack of success of big passers in general, is that teams that get behind early have to air the ball out to try to close the gap, while teams that get ahead try to slow the game down by running and watching the clock tick away.

These stats are all pretty surprising, but what do they mean? Obviously, it means that we generally overvalue the passing game. More importantly, chances are pretty good that you have a leak in your handicapping that is costing you money. Unless you are basically ignoring passing statistics, or at least the probable passing performances of the two teams in a given game, then you are making decisions based on information that hasn't proven itself to be worth making a decision on. At least for this season, anyway.

The danger of including statistics like this, and especially one that can be as easily seductive as passing yards can be, is that they could sway your decision on a game. If you decide to bet on New Orleans, for example, because they have a huge advantage over almost everyone in the passing game, then you are making a decision based on a factor that may not have been proven to actually accurately predict the outcome of games against the spread. That could lead you to making bets that you later regret. Taken to an extreme, it would be like saying that this car is clearly faster than that one because it is red. It may look nicer because of the color, and it may be better suited for some purposes because of the color, but the color clearly has nothing to do with how fast it is. Similarly, passing yards also don't clearly seem to have anything to do with whether a team will cover a spread.