NFL Power Rankings Week 15: Identifying the League's Most Impressive Teams

No matter how much you know about the NFL, you're still bound to be surprised by the time the season wraps. That's part of what makes the sport so compelling—teams that were supposed to struggle can emerge as playoff contenders, and vice versa.

Here are the three most surprisingly impressive teams of the 2011 season, teams that have exceeded expectations despite having seemingly so much going against them in September.

San Francisco 49ers

The Niners ended 2010 with a 6-10 record and started the 2011 season with a new head coach, Jim Harbaugh, who had yet to speak with the majority of his offensive and defensive starters.

That didn't seem to bode well for the NFC West squad, with growing pains predicted for this first year under Harbaugh.

Instead, San Francisco has managed to overcome nearly every obstacle between them and a winning season that they've faced in recent seasons.

Quarterback Alex Smith is finally in a system that plays to his strengths while minimizing his weaknesses, running back Frank Gore is healthier and more effective than he's been in some time, and the San Francisco defense—one of the league's best for seasons—finally has an offense that matches their talent level.

At 10-3, the Niners have clinched their division and with it a playoff spot. While everyone focused on 2011 being the year that the Detroit Lions finally turn things around, it ended up being the Niners who ended up the most-improved team.

Houston Texans

The Houston Texans found themselves in a rare advantageous situation as far as the AFC South is concerned, with Indianapolis Colts quarterback Peyton Manning out for the season, making the division wide open to any worthy takers.

While the Texans started the season as favorites to nab the title, many observers pointed to the fact that the team had come so close to playoff berths and division leadership in the past, they haven't been able to finish the job.

Until this season, apparently, that is. The Texans started strong despite star running back Arian Foster struggling with hamstring issues in the early weeks and wide receiver Andre Johnson suffering from similar issues off and on throughout the year.

Once again, quarterback Matt Schaub was an effective passer, once again their defense was tough and once again, they could run the ball seemingly at will.

However, things could have gone terribly wrong. The team has spent most of their season without Johnson, their leading receiver, they lost linebacker Mario Williams to a torn pectoral muscle and, in consecutive weeks, quarterbacks Schaub and Matt Leinart went down for the season with injuries of their own.

But it doesn't seem to have phased the Texans, who, behind rookie quarterback T.J. Yates, clinched a playoff spot and the AFC South title with their Week 14 win over the Cincinnati Bengals.

Now the team that has never seen the postseason in franchise history is in full control of their division and are the top squad in the entire AFC. It's both surprising and impressive.

Denver Broncos

The Denver Broncos seemed dead in the water earlier this season, headed into their Week 6 bye with a 1-4 record and little promise to turn things around.

Quarterback Kyle Orton was benched as a result, replaced by backup Tim Tebow, who, despite having a number of wins when starting in 2010, wasn't pegged to be very successful when it came time for him to lead the Denver offense. 

Instead, Tebow assisted in engineering one of the biggest turnarounds of the season, taking over in Week 7 and helping the team along to seven wins and one loss since that time.

The team is currently on a six-game win streak that has found them atop the AFC West and apparently playoff-bound, something thought entirely impossible for the team with Tebow under center. 

According to the NFL Network's Michael Lombardi, the Broncos' initial plan was to start Tebow for a few weeks to appease the fans who had been calling for him to take the reins, but ultimately they were to clean house, divesting themselves of Tebow and all remnants of the Josh McDaniels era as the season wore on.

Instead, Tebow has found ways to put his team in the position to win, albeit not until the waning minutes of the fourth quarter. Despite completing fewer than 50 percent of his passes so far this year, he's managed either a passing or rushing touchdown in every game he's played and has thrown only two interceptions.

While there are a number of factors that have made the Broncos a success—an ever-strengthening defense and fielding the league's overall top rushing offense, for two—Tebow's presence on the field has provided a significant spark to a team that seemed destined for nothing more than obscurity just a few months ago.

NFL Power Rankings, Week 15*
 
1. Green Bay Packers
2. New Orleans Saints
3. Baltimore Ravens
4. Houston Texans
5. San Francisco 49ers
6. Pittsburgh Steelers
7. New England Patriots
8. Atlanta Falcons
9. New York Jets
10. Denver Broncos
11. Detroit Lions
12. New York Giants
13. Cincinnati Bengals
14. Tennessee Titans
15. Arizona Cardinals
16. Dallas Cowboys
17. Seattle Seahawks
18. San Diego Chargers
19. Miami Dolphins
20. Buffalo Bills
21. Oakland Raiders
22. Chicago Bears
23. Minnesota Vikings
24. Jacksonville Jaguars
25. Carolina Panthers
26. Kansas City Chiefs
27. Philadelphia Eagles
28. Tampa Bay Buccaneers
29. Washington Redskins
30. Cleveland Browns
31. St. Louis Rams
32. Indianapolis Colts

*Subject to change pending the outcome of Monday night's Rams vs. Seahawks contest.