One of the most interesting aspects of the 2011 season has been the play of the defenses.
There have been surprises such as the Houston Texans and there have been late surges from teams such as the Denver Broncos.
The rest of the season and playoffs will depend on how these defenses perform down the stretch.
I have used criteria such as points per game, yardage per game, interceptions and sacks to generate defensive power rankings for the 2011 season.
There is no doubt that the worst team in the league is the Indianapolis Colts.
They have the worst defense in the league and to make matters worse, they have one of the worst offenses in the league.
The Colts can't stop anyone and when they do, they can't score enough points to win.
The Panthers defense is pitiful and has lost them a number of games this season.
They give up 27.7 points per game and more than 370.1 yards per game. They are ranked No. 31 and No. 26 in the league in those respective categories.
The Panthers have the No. 5 offense in the league but their defense drags them down so far that Carolina is 3-8 on the year.
The Buccaneers have been downright bad this season. They give up the second most yards per game in the league and 26.5 points per game.
Not to mention Chris Johnson, someone who has been non-existant this season, ran all over them in Week 11.
The defense as well as injuries are the reason for the Buccaneers downfall this season.
While the Minnesota Vikings have a decent run defense, their pass defense drags them down.
The Vikings secondary has been ravaged by injury and will only get worse as the season drags on.
The Vikings give up more than 26 points per game and their offense can't put up anywhere near that many points.
While the New York Giants have a winning record, you could not tell by looking at their defense.
They give up more than 25 points per game. Both their passing defense and their running defense are mediocre at best.
If they expect to make the playoffs, the defense better shape up quickly.
There is no doubt that part of the reason the Buffalo Bills fell of the face of the earth is that their defense is bad.
They give up 25.5 points per game, which is the fifth most in the league.
Their sole redeeming quality is the fact that they have the second most interceptions in the league at 16.
The St. Louis Rams no doubt have the worst rushing defense in the league.
Running backs like DeMarco Murray and Beanie Wells have been running all over them this season.
At least their passing defense is decent; it is the eighth best in the league.
If their running defense wasn't so bad, maybe the Rams wouldn't be 2-9. They surely wouldn't be losing to teams like the Arizona Cardinals.
The Chargers have lost six games in a row. The defense has to share some of the blame for that.
The Chargers give up 25 points per game.
One of the main reasons for this is that the Chargers have a very weak running defense. They give up more than 130 yards per game on the ground.
The Chargers are fading fast and if they want a shot at the playoffs, the defense will need to step it up.
The Oakland Raiders defense has not been very good this year. Luckily, the offense has been able to secure three wins in a row for the Raiders.
The Raiders give up 24.9 points per game on average.
The Raiders pass defense and run defense are both below average.
However, they do have 32 sacks on the season, which is fifth in the league.
Things have not been going very well for the Chiefs defense this season. They give up more than 24 points per game.
To compound the problem, the Chiefs lost their biggest offensive weapon in Jamaal Charles and starting quarterback Matt Cassel.
The Chiefs can't really win when backup Tyler Palko and the offense has to put up more than 24 points to win the game.
The Arizona Cardinals have not lived up to expectations this year and part of the reason for this is poor defensive play.
The Cardinals give up almost 375 yards per game and they don't get many turnovers to make up for it.
Luckily for the New Orleans Saints defense, the Saints have the best passing offense in the league.
The Saints give up 22.9 points per game. This is mostly due to their weak passing defense which gives up 253.7 yards per game in the air.
Not to mention, they don't force turnovers very often. They only have six interceptions on the year. This isn't really a problem though, because the Saints offense is so good.
Despite the fact that the New England Patriots have the worst passing defense in the league, they do get a lot of interceptions, 16 in fact.
The Patriots defense doesn't really need to be very good. They have one of the best offenses in the league backing them up.
They just need to stop the opponent every once in a while and Tom Brady will take care of the rest.
Like their offense, the Seahawk defense isn't all that great. They don't lose games for Seattle, but they are by no means winning games either.
The defense gives up 21.1 points per game. Their rush defense is much better than the pass defense, so opponents have been able to exploit this weakness.
The "Dream Team" has not lived up to expectations and part of that blame falls on the defense.
The Eagles give up an average of 22.8 points per game.
Their improved passing defense has given up 234.4 yards per game, but their running defense isn't much better at 110.3 yards per game.
The Eagles are pretty average on defense, but they do get a lot of interceptions.
The Lions have been one of the surprise teams of the 2011 season.
One of the reasons for this has been their pass defenses.
They have the No. 6 ranked pass defense in the league. They have generated 16 interceptions this season, something that makes opposing quarterbacks very wary.
Unfortunately, their rushing defense is not quite as good and teams have found ways to exploit this.
Now that Ndamukong Suh has been suspended for two games, their stock has fallen a little bit.
The Dallas Cowboys have been playing well recently and the defense has been a big part of that.
They give up 20.5 points per game and 331 yards per game, two stats that are very respectable.
Neither their running or passing defense is very overwhelming, but the two combined makes them a balanced defense.
Something that sets them apart is interceptions. They have 14 on the season which gives their offense a better chance of scoring more points.
The Bears, like the rest of the NFC North, have a pretty average defense. They give up 21.1 points per game, but their defense has scored three touchdowns this season.
They also have 16 interceptions, which gives the Bears a nice advantage on offense.
Chicago will need the defense to step up now that Jay Cutler is injured.
Once again, the New York Jets have failed to live up to expectations. Their defense is not bad, but by no means is it great. They give up 21.9 points per game. Fortunately, they don't give up many yards.
Opposing offenses are averaging less than 320 yards per game against the Jets this season.
If they improve their passing defense, they would be even better.
The Green Bay Packers are considered to have one of the worst passing defenses in the league.
However, they lead the league in interceptions and its not even close. The Packers have 22. That is an incredible advantage for the offense.
Not to mention, they only give up 20.6 points per game.
They could give up 30 and the Packers would still be undefeated.
No, the reason that Tim Tebow wins games is not that he is the greatest quarterback ever. The Broncos defense is a big factor in his success.
In the last three games, the Broncos opponents have not scored more than 13 points.
Sure, they give up a lot of yardage, but they get a lot of sacks and have not given up many points recently.
Although they are not as good as last year, the Falcons are still good, especially defensively. They give up the ninth fewest points per game in the league.
What really makes the Falcons stand out is their rushing defense.
They only allow 83.5 yards per game on the ground, forcing teams to beat them in the air.
Before Week 12, the Redskins lost six games in a row and it was by no means the fault of the Redskins defense.
They give up only 20.2 points per game and 330.6 yards per game. They have also forced 13 fumbles on the season, which is fourth most in the league.
If the offense wasn't so bad, the Redskins would be winning a lot more games.
Despite the fact that the Titans offense has been disappointing, the Titans defense has been stellar.
They only give up 19.3 points per game.
The Titans do give up a lot of yardage, but the fact that they don't give up many points per game makes up for it.
The Titans have only given up five rushing touchdowns on the season, showing that they have one of the best rushing defenses in the league.
Only the Dolphins and the 49ers have given up fewer touchdowns.
The Miami Dolphins are actually better than their record shows and have won three of their last four games.
Part of the reason for this is the fact that their defense is so good. They only give up 18.7 points per game mostly because their rush defense is so effective.
They give up the seventh fewest rushing yards in the league.
It's not difficult for Matt Moore to put up more than 19 points in order to win a game.
Defensively, the Browns have been great this season. Their offense is a different story.
The defense gives up 19.6 yards per game and the Browns give up the fewest passing yards per game. Their running defense is not so great. They give up 138.6 yards per game on the ground.
If Colt McCoy gets things figured out, the Browns would actually be good for a change.
The Bengals may be one of the most underrated teams in the league. They are 7-4 and their defense has been a big part of their success.
They give up the fifth fewest yards per game and the eighth fewest points per game.
The real test comes in the next two weeks when they play the Steelers and the Texans.
While the Jaguars have been horrible offensively, their defense has been solid. They only give up 18.2 points per game.
If the offense could actually score a few points, the Jaguars would have more than three wins.
With the change at head coach, maybe things will improve.
Over the past few years, there has been few things more consistent than the Steelers defense. The Steelers give up the fourth fewest points per game in the league at 17.1.
However, they also give up they second fewest yards per game and they do it without getting many interceptions or sacks either.
If they start getting turnovers, the Steelers would be a real threat to go deep into the playoffs.
The Ravens have been excellent this year, even with arguably their best player, Ray Lewis being injured.
The Ravens give up the third fewest points per game in the league and lead the league in defensive touchdowns with four.
This is not a defense a team wants to go up against.
One of the main reasons for the San Francisco 49ers' success this year has been the fact that their defense has been so good.
The 49ers give up the fewest points per game in the league and lead the league in forced fumbles.
If their defense continues to play the way it has been playing, the 49ers will go deep into the playoffs.
The Houston Texans have one of the most consistent defenses in the league. They are not only consistent, but they are good as well.
They have the No. 2 ranked passing defense and the No. 4 ranked rushing defense.
They only give up 16.3 points per game. There is no doubt that they are the most underrated defense in the league.