Inside Slant: Small Super Bowl field

Voting for ESPN.com's weekly Power Rankings this season has revealed a sobering set of tiers. A handful of elite teams have rotated through the top of the rankings, a few others consistently have remained above .500 and then there has been everybody else.

The postseason, although still forming, portends a similar theme.

Twelve teams will receive playoff bids, six from each conference. But even while recognizing the history of upstart champions, I'm having a hard time looking past a handful of likely winners for Super Bowl XLVIII.

The Seattle Seahawks, who haven't lost at CenturyLink Field since roughly 1937, are on their way to clinching the NFC's home-field advantage. (They could do it a early as Sunday with a victory over the Arizona Cardinals.) Who among their possible opponents could go to Seattle and knock them out?

It's difficult to envision big things for the New Orleans Saints, who have been outscored 61-23 in their past two road games and are in danger of losing their presumptive NFC South title to the Carolina Panthers. And because we're in the holiday season, we simply won't discuss the middling title chances of the eventual NFC North and NFC East champions.

The Panthers and San Francisco 49ers both fit the profile of playoff upstarts. The Panthers have won nine of their past 10 games, and the 49ers are riding a four-game winning streak. The Panthers were competitive in a Week 1 home loss to the Seahawks, and the 49ers beat them two weeks ago at Candlestick Park.

Recent history suggests a tough road for both teams, however. The Seahawks have won five consecutive home playoff games and have lost only once in the postseason at CenturyLink, a one-score game in the 2004 wild-card round. At the moment, the Seahawks must be considered heavy, heavy favorites.

The AFC presents perhaps a bigger dichotomy of playoff contenders. The Denver Broncos have demonstrated clear superiority to the conference's next-best team, the Kansas City Chiefs, by sweeping their regular-season series. The New England Patriots beat the Broncos in overtime at home, but they are no longer the same team after losing tight end Rob Gronkowski to a knee injury.

The Indianapolis Colts and Cincinnati Bengals? Both are 9-5, but both have played at a .500 clip over their past six games and have substantial roster holes caused by injuries. In reality, the team that might scare the Broncos the most is the same team that knocked them out of the 2012 playoffs: the Baltimore Ravens.

The Ravens have won four consecutive games and five of their past six and might be hitting their stride at the perfect time. They did not match up well in the teams' regular-season opener, a 49-27 Broncos victory, but we've seen this late-season act before.

Much could change in the next two weeks, of course. But if we're taking stock on the eve of Week 16, the realistic Super Bowl field seems relatively small.