49ers vs. Cardinals preview: San Francisco defense needs to make statement on MNF

If defense wins championships, then the San Francisco 49ers will have an opportunity to prove they belong in the conversation of best team in the NFL with a convincing win against a depleted Arizona Cardinals team on Monday Night Football at University of Phoenix Stadium.

The 49ers' defense has been good in 2012, but they haven't been as dominant as they were a season ago when they ranked No. 1 in the NFL in yardage differential. In 2012, they're ranked 14th, meaning that 13 teams do a better job of outgaining their opponents in total yardage. That's what the 49ers have done best over the past two seasons, and against the Cardinals, they'll need to get back to it.

With respect to the linebackers, the 49ers have the best in the league between Ahmad Brooks, NaVorro Bowman, Patrick Willis and Aldon Smith. Those four have managed to make life difficult for opponents and have eight of San Francisco's 11 team sacks on the season through seven games, and will be ready to show what they can do with the world watching.

How Willis fares will be of particular interest. The defensive captain and team leader has been a tackling machine like always in 2012, amassing a team high 42 tackles, but he has yet to record a sack of his own on the year. It's worth noting that he's still made the Pro Bowl in each of his five seasons when he had less than two total sacks in two of those campaigns.

The Cardinals were dismantled by the Minnesota Vikings in Week 7 and were held to just 230 yards passing. Injuries to Kevin Kolb, Ryan Williams and Beanie Wells have hurt their continuity on offense and caused some inconsistency in that department. With the 49ers among the best in the league in rushing yards allowed with 98.9, they figure to make Arizona one dimensional and dictate the flow of the game.

With a win, the 5-2 Niners will have an opportunity to separate themselves in a surprisingly competitive NFC West division. Just like they did a season ago, it will be the defense that will carry them toward potential postseason success.

Those aspirations start by winning key division games like the one coming up on Monday night.