Four weeks is a pretty small sample size in an NFL campaign, but here are a few things that have either become obvious to us, or could happen through the last 13 weeks of the 2012 NFL regular season. The Arizona Cardinals are the best team in the NFL. Well ... not really. The Cards need an actual quarterback first. But when it comes to their won-lost record (which is what some would have you believe is al that matters), no team is better than Arizona over the NFL's last 13 games. Believe it or not, the Cards have a lofty 11-2 record over that time, and they're doing it with defense, defense, defense. Patrick Peterson is the best cornerback in the game right now -- sorry, Mr. Revis and Mr. Asomogha -- and the Cardinals' pass-rushers are just short of ridiculous. Defensive coordinator Ray Horton has put together a defense inspired by his mentor, Pittsburgh's Dick Lebeau, but with a few new wrinkles. You'll see Peterson playing iso (no safety over the top) coverage against an opponent's bets receiver every week, and stalwarts like Dockett and safety Adrian Wilson take the playbook on the field every week. it's Arizona, not San Francisco, that currently sports the only undefeated mark in their division, and as much as defense is the key, that concept has spread around the NFC West. The NFC West is the new Black-and-Blue Division. This division used to be the NFL's patsy, but no more. The Cardinals, Seattle Seahawks, San Francisco 49ers, and St. Louis Rams are putting together strong efforts every week with similar gameplans -- starting with different defenses that stuff opposing offenses on a regular basis. We were introduced to the defense Vic Fangio runs in the Bay Area last season, and people are starting to get wise to Arizona, but it's very unwise to sleep on what's happening in Seattle with Pete Carroll's multiple fronts and talented secondary. And with Jeff Fisher changing the culture in St. Louis, strong front sevens and opportunistic pass defense has become the norm. Any invitation to play an NFC West team these days also comes with a complimentary smack in the mouth. It's quite possible that three of the NFL's best defenses reside in the NFC West -- and the Rams are closing fast. Even at 0-4, the Saints aren't as bad as they look. Well, Steve Spagnuolo's defense is a major problem, and it's clear that even Drew Brees can only do so much without a head coach and offensive mastermind like Sean Payton to go over things in each game. But the Saints have lost their four games by a total of 20 points, and at least the passing offense is still prolific. This is Spagnuolo's first year in New Orleans, and it's worth remembering that the 2007 New York Giants defense he coached (you know, the one that went on to help win Super Bowl XLII) started out by giving up 80 points in its first two game before righting the ship. Now, the 2012 Saints don't have the pass rushers the Giants did (or do), but as the Saints adjust to one of the more bizarre off- and in-seasons in the history of the league, they'll start to find the middle. We're not suggesting that the Saints are looking toward a playoff berth, but this is an 0-4 team in record only. When the playoffs start, Colin Kaepernick will be the 49ers' starting quarterback. The 49ers came very close to the Super Bowl last year with Alex Smith at quarterback, but two generally unrepeatable aspects -- a huge advantage in turnover ratio and a great deal of injury luck -- may have Jim Harbaugh's team requiring more of its passing offense this year. And though Smith has proven to be an effective "Don't-screw-it-up" guy in Harbaugh's system, he's still struggling to fit simple passes into tight windows, a skill required of every great NFL quarterback. In their 34-0 beatdown of the New York Jets on Sunday, Harbaugh rolled Kaepernick, a second-round pick in 2011 , out on the field to poke Rex Ryan in the eye, but there's more to the Nevada alum's game than running around the field. Kaepernick is raw, but he can make every throw, and don't be surprised if Harbaugh decides that the risks involved in a more expansive passing game can be outweighed by the team's great running game and defense. The Bears will leapfrog the Packers in the NFC North. There are times when the Chicago Bears look like a hot mess on the field, but when they put it all together, as they did against the Dallas Cowboys on Monday night, they're very tough to beat. The Bears' defense is as effective and multiple as it's ever been through Lovie Smith's tenure, and as long as Jay Cutler can keep his head -- and Mike Tice can remember that protection schemes are a good idea (as he generally does in the second half of each season), it's quite possible that Chicago will take the NFC North from the Packers, whose defense has not caught up to an offense that is struggling in comparison to last season. Bill Belichick is the best NFL coach since Bill Walsh.