Funny, isn’t it?

The Dallas Cowboys shocked everyone (including the heavily favored New York Giants) with a 33-20 win, good for their second win of the season. In Week 10.

The San Francisco 49ers were expected to run through the NFC West without a challenge. They’re tied for last place in the division through nine games.

The Oakland Raiders, which has been a predictably losing team for the past few years, are tied for the longest win streak in the league and sit atop the AFC West.

The Tampa Bay Buccaneers are 6-3.

The NFL changes so rapidly on a week-by-week basis that it’s difficult to put it into words. “Parity” is a word thrown around a lot, suggesting that the gap between the league’s best teams and worst teams is closing. It seems to be the case, as teams such as the Browns, Rams and Jaguars continue to impress. But although these teams are getting better, they’ve certainly had ample opportunity to learn from the faults of others. Take the Cowboys. Sure, the team is talented: Jerry Jones would have nothing less than some of the most skilled players grace his cathedral of a stadium. And the media gave the team elite status because Tony Romo looked great in the regular season. Dallas has always been talented, but has only one playoff win in the last 10 years to show for it.

The Minnesota Vikings thought that bringing Brett Favre back would give them the best chance of returning to the NFC Championship game. And they have suffered some setbacks this year, with the injury to Sidney Rice and the Minnesota installment of “The Randy Moss Show.” But the Vikes instead will most likely be a sub-.500 team.

The stumbles of these supposed top dogs have given more light to the underdogs of the 2010 season such as the Chiefs, Seahawks, Rams and Raiders. And perennial contenders such as New England, Pittsburgh and Indianapolis are still looking down at the rest of the league. But the reason for this season’s parity is the progression of the lower tier of teams. Even teams such as Detroit and Buffalo, which had single digit wins early on in the season, stay competitive in most of the games. But without normal stalwarts of the Vikings and Cowboys, these teams have taken their place in the mix.

— Edited by Emily McCoy.