One of the most persistent storylines that dogged the Cowboys until the end of the 2009 season was the notion of the December swoon. The story had gained an almost mythic quality: as soon as the calendar turned to December, the Cowboys were expected to collapse. More specifically, the Cowboys' high profile quarterback was expected to collapse and the tag of a 'sunshine superman' - who only performs well early in the season - became increasingly associated with Tony Romo.

Of course, Tony Romo put that story to bed permanently in 2009, but one of the more nefarious allegations that live on like the undead in the darkest recesses of the interwebs is that Romo pads his stats against weak teams and underperforms against quality teams.

Irrefutable fact or vicious slander? Time to set the stat hound loose to sniff out the truth as we slice and dice Tony Romo's performance against better and lesser opponents.

Let's put the stat-padding story out of its misery right away. Tony Romo's career passer rating against quality opponents (teams that won 9 or more games that season) is 94.1, only marginally lower than his 95.5 career average. Nothing to see here, move along, ladies and gentlemen, move along.

A closer look at the splits by opponent W/L record in the table below shows that Romo does have better numbers against the truly terrible teams in the league. But which QB doesn't?

Interestingly, the only drop-off we see is against teams that finished the season 8-8, and that's due to four specific divisional games. In each of Romo's first four years as a starter ('06-'09), there was always one team in the division that finished 8-8. And each year, Romo picked that team for a little INT extravaganza:

2006 vs Giants, L 22-36, 2 TDs, 2 INTs
2007 vs Eagles, L 6-10, 0 TDs, 3 INTs
2008 @ Redskins, W 14-10, 1 TD, 2 INTs
2009 vs Giants, L 31-33, 1 TD, 3 INTs

In 2010, Romo did not face a team that finished 8-8, which probably saved him from a couple more INTs. That is, if you subscribe to the theory that randomly assembled stats from the past are indicative of the future.

Here's Romo's full breakdown by opponent wins.