Despite old mantras, the NFL has shifted dramatically over the last 10 years. Things are becoming much more offense-oriented—and it's tough to win in this league without an elite quarterback.
While San Francisco has the edge in the defense department, offense is New England's bread and butter.
The Pats have the best offense in the NFL, ranking first in yards (426) and points (36) per game. Both numbers lead the league.
The Patriots are led by arguably the best quarterback in football in Tom Brady, but they've also built a powerful rushing attack this season. That balance makes them all the more dangerous.
The 49ers are still working on finding their elite quarterback, but it hasn't been a huge issue this season. They're led by Frank Gore, whose hard-nosed approach has San Fran's rushing attack the second-best in football—averaging 162 yards per game.
And while Colin Kaepernick is no Tom Brady, he has improved the 49ers passing game. Since replacing Alex Smith, Kaepernick is 4-1 and averaging 257 all-purpose yards a game.
Just like with their defenses, these teams' offenses are on different levels. But they still find plenty of ways to put up points and win games.