The AFC is getting all the love.  Almost every power ranking I've seen has way more AFC teams in the top 10 than the NFC teams. 

You have the Steelers, Ravens, and Jets all noted for their defense.  Well, what happens when we remove the points allowed and yards per game?  Points allowed isn't purely a defensive stat and neither are yards per game. 

Let's take a look at how the teams rank by adjusted yards allowed per play.  The adjusted is there because every take-a-way is close to about 40 yards.  So here are the top defenses in the NFL.

POS Team Plays Yds/Game Yards INT FUMB Adj. Yds/Play
1 Chicago Bears 571 301.9 2717.1 14 10 3.08
2 New York Giants 510 270.2 2431.8 10 10 3.20
3 Pittsburgh Steelers 569 315.4 2838.6 11 10 3.51
4 Philadelphia Eagles 575 325 2925 16 5 3.63
5 New York Jets 570 306.7 2760.3 5 11 3.72
6 New Orleans Saints 523 277 2493 6 7 3.77
7 Green Bay Packers 576 326 2934 14 5 3.77
8 San Diego Chargers 532 274.7 2472.3 8 3 3.82
9 Tennessee Titans 617 350.8 3157.2 14 6 3.82
10 Carolina Panthers 594 326.8 2941.2 11 5 3.87
11 Cincinnati Bengals 557 329.3 2963.7 10 8 4.03
12 Oakland Raiders 544 309.6 2786.4 5 9 4.09
13 Detroit Lions 571 353.2 3178.8 9 11 4.17
14 St. Louis Rams 559 325.8 2932.2 8 7 4.17
15 Miami Dolphins 558 314.1 2826.9 6 5 4.28
16 Minnesota Vikings 549 310.8 2797.2 8 3 4.29
17 Baltimore Ravens 548 316.4 2847.6 8 4 4.32
18 Cleveland Browns 596 358.6 3227.4 10 6 4.34
19 Tampa Bay Buccaneers 558 353.8 3184.2 14 5 4.34
20 Indianapolis Colts 563 344.2 3097.8 9 7 4.37
21 San Francisco 49ers 573 331.4 2982.6 8 4 4.37
22 Atlanta Falcons 531 343.4 3090.6 14 5 4.39
23 Kansas City Chiefs 595 344.7 3102.3 7 5 4.41
24 Seattle Seahawks 616 376.9 3392.1 7 9 4.47
25 Arizona Cardinals 630 401.8 3616.2 10 8 4.60
26 Washington Redskins 628 415.3 3737.7 9 10 4.74
27 New England Patriots 604 390.8 3517.2 10 5 4.83
28 Dallas Cowboys 546 354 3186 7 6 4.88
29 Buffalo Bills 607 373.7 3363.3 2 6 5.01
30 Denver Broncos 578 372.9 3356.1 5 5 5.11
31 Jacksonville Jaguars 543 387.2 3484.8 8 4 5.53
32 Houston Texans 587 409.7 3687.3 5 3

5.74