1. Baltimore Ravens: They are 2-2 and they lost very close games in back-to-back weeks. This was my preseason pick to surprise and improve drastically. They have the top defense in the league again, and are currently second in their division. Baltimore came oh-so-close to beating Pittsburgh in Pittsburgh but lost in overtime, and lost a fourth-quarter lead to the Titans last week. I still believe this is a playoff team and they will prove that before the end of the season.

2. Pittsburgh Steelers: They are 4-1 and still leading the AFC North. They've consistently been in the top 10 in our Terrific 10 and though their offense hasn't been fantastic, their defense has been stellar. They've allowed 231.6 yards of offense per contest and they have played some very good opponents. Unfortunately for the Steelers, it's not going to get any easier and they are extremely banged up. Regardless, I'm still impressed with what they've done.

3. New York Giants: So much for a dropoff after losing Michael Strahan and Osi Umenyiora, eh? This team is 4-0 and there isn't a team out there right now that can stop them. They're so good that they suspended their star wide receiver for a game and did not miss a beat. They've held opponents to a 32% conversion rate on third downs, which is in the top five in the league. I'm anxious to see if this defense can keep it up.

4. Carolina Panthers: Take a look at the standings -- the NFC East is getting a lot of attention as the best division in the NFL, but the NFC South isn't far behind. The Panthers currently lead that very tough division at 4-1. I've heard from a few readers that we haven't given them enough love in our power rankings (trust me, I've put in a good word and I think they'll make a move). They put a lot of emphasis on improving the offense in the offseason, but their defense has been terrific. They've allowed just 70 points, fourth fewest in the league and theire defense is reminiscent of the one they had back at the beginning of the decade.

5. Tennessee Titans: At the top of the AFC South, the Jacksonville Jaguars are nowhere to be found and the Indianapolis Colts are two-fourth quarter comebacks away from being 0-4. It's looking more and more like the Titans may run away with this division. The Titans are seventh against the pass and 11th against the run. They are one of just three teams to force 10 or more fumbles this season and they've allowed the second fewest amount of points this season.

The teams listed have a combined record of 19-3. Compare that to the top five offensive teams in the league -- Giants, Broncos, Cowboys, Saints and Cardinals -- who have a combined record of 17-7. If you take the Giants out of the equation, since they are the only team in both categories, the records fall to 17-3 and 13-7. Taking the latter into effect, the winning percentage for the best defensive teams is 20 percent higher than the best offensive teams. That's a pretty significant difference.

Now that we are five weeks in, I'd say we've got a pretty good sample size. Over the years, casual fans have lobbied for more offense and the NFL has tweaked the rules to favor the offense. Since 2000, only two top picks have been defensive players (Mario Williams in 2006 and Courtney Brown in 2000). Even in an era where the offense makes the headlines, it's the best defensive teams that end up making significant strides and winning games.