Upsets less frequent during division games

The Denver Broncos got off to a 7-3 start in the 2004 season -- including a 31-3 spanking of the rival Oakland Raiders on the road. For Week 12, they were set to host the Sunday night game, with the struggling 3-7 Raiders coming into Invesco Field.

Piece of cake, right?

Not so fast.

The Oakland passing attack had a great night, especially Jerry Porter, and Denver's Jason Elam missed a game-winning field goal, giving Oakland a 25-24 win. It was another in a long line of Denver-Oakland upsets.

Or was it? It sure seems like the Broncos and Raiders have a habit of playing close games, even when one team is much better than the other. Is that true? And in general, are division games more likely to be upsets than non-division games?

To find out, I went back to 1995, when Carolina and Jacksonville joined the NFL, and included both regular-season and postseason games. When two teams play, how often does the team with the better overall record that season actually win that specific game?

Since 1995, discounting games in which the teams end the year with the same record, the answer is 72.7 percent of the time. However, looking only at division games, the answer is 74.1 percent of the time. Upsets are actually less frequent during division games.

However, some rivalries have produced more upsets than others. That happens to include both of the rivalries that will be featured on the opening doubleheader of Monday Night Football. When Denver plays Oakland, the team with the better record has won only 67 percent of the time. The same goes for games between Green Bay and Minnesota.

That's a small difference, and given the sample size (26 and 27 games, respectively), it could be totally meaningless. However, other rivalries feature upsets far more frequently. In one very famous rivalry, the team with the better record has actually lost the majority of the games. Here are the rivalries in which upsets have been the most frequent since 1995 (minimum 20 games):

Think that might contribute to the arguments between Cowboys and Redskins fans? There are only two other division rivalries in which the lesser team has won the majority of games: Arizona-San Francisco (14 games) and Houston-Jacksonville (10 games).

In other rivalries, the better team wins pretty much every time the two teams meet. The five rivalries that most often play out according to season win-loss records include the dominant rivalry of this decade, even though it hasn't been a division rivalry since 2001: Colts-Patriots.

A few more fun rivalry facts:

• The most frequent matchup over the past 13 seasons has been the Giants and Eagles, who have played 28 times.

• There are three rivalries that have included 12 games even though the teams were not in the same division either before or after the 2002 realignment: Packers-49ers, Jets-Raiders, and Broncos-Patriots.

• The rivalry with the most games in which every single game has been won by the team that ended the season with a better record is Baltimore-Jacksonville (15 games).

Aaron Schatz is president of Football Outsiders Inc. and the lead author of "Pro Football Prospectus 2008," now on sale online and in bookstores everywhere.