Yes they have an awesome defense.
Yes their special teams can turn games around in a heartbeat.
BUT, the X factor is Rex Grossman, the guy is way too inconsistent at this point this season. He started off the season hot and then went stone cold throwing almost as many picks as Ben did during the last 6 weeks. 2 Weeks ago the guy had a 1.3 QB rating and threw for like 30 yds. Last night he was better BUT the Rams defense is average at best. Bulger had a better game against the Bears defense than Grossman did against a sub par Rams defense.
Im just saying with how hot the Cowboys have been, don't count out Seattle, and watch out for the Saints, I'd be awful leary about crowning them too early. They may very well get to the super bowl, but if Rex continues to struggle, especially in crucial situations like the playoffs, they could be ousted earlier than expected.