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Week 11 was not a good week for the top two defenses in the NFL.

The Houston Texans won last week’s game, 43-37, in overtime versus the Jacksonville Jaguars. The Jaguars offense scored seven times in 14 possessions against the Texans. It was the worst defensive performance of the Texans “D” since their loss to the Green Bay Packers, 42-24 in Week Six. The seven scores allowed by their defense was the most allowed this season.

The Chicago Bears suffered a 32-7 home defeat at the hands of the San Francisco last Monday night. The Bears allowed the 49ers offense to score six times in 10 possessions, the Bears’ defense worst performance of 2012.

These bad performances by the Texans and Bears defenses opened the door for the 49ers defense to take over first place in this week’s NFL STOP Factor rankings. The San Francisco defense allowed the Chicago offense to score only once in 10 possessions. The 49ers jumped ahead of Houston and Chicago in the rankings with a 74.3 STOP Factor ranking.

(The STOP Factor is based on the premise that it is the defense’s job to stop their opponents from scoring on each possession. To get a team’s STOP Factor, you divide the number of times a defense stops the offense from scoring – offensive unit TD or field goal – by the number of total possessions by the opposition.)

Following is each NFL teams’ STOP Factor. Listed is how many times each team stopped the opponents from scoring, the number of possessions their opponents had, and the percentage of possessions that each team prevented the other team from scoring (stats are through Week 11 games; games for Thanksgiving Day are not included in this week’s totals).

Team, Opponents’ scoreless possessions/opponents’ possessions, STOP percentage

1. San Francisco 74.3 (75 stops in 101 possessions)

2. Houston 73.6 (89 stops in 121 possessions)

3. Chicago 73.1 (87 stops in 119 possessions)

4. Seattle 71.0 (71 stops in 100 possessions)

5. Denver 70.1 (82 stops in 117 possessions)

6. Arizona 70.0 (84 stops in 120 possessions)

7. Atlanta 68.2 (73 stops in 107 possessions)

8. Tampa Bay 67.8 (78 stops in 115 possessions)

9. San Diego 66.3 (69 stops in 104 possessions)

10. Cleveland 65.8 (77 stops in 117 possessions)

11tie. Green Bay 65.5 (74 stops in 113 possessions)

11tie. Miami 65.5 (76 stops in 116 possessions)

13. Pittsburgh 65.3 (64 stops in 98 possessions)

14. New England 64.5 (71 stops in 110 possessions)

15. Baltimore 63.5 (73 stops in 115 possessions)

16. Cincinnati 63.3 (69 stops in 109 possessions)

17. Minnesota 63.0 (68 stops in 108 possessions)

18. New York Giants 62.9 (66 stops in 105 possessions)

19. Dallas 62.4 (63 stops in 101 possessions)

20. New York Jets 62.0 (67 stops in 108 possessions)

21. Detroit 61.2 (63 stops in 103 possessions)

22. Philadelphia 61.1 (66 stops in 108 possessions)

23. St. Louis 60.2 (62 stops in 103 possessions)

24. Washington 59.5 (66 stops in 111 possessions)

25. Indianapolis 59.2 (61 stops in 103 possessions)

26. New Orleans 56.4 (62 stops in 110 possessions)

27. Kansas City 55.8 (58 stops in 104 possessions)

28. Buffalo 55.1 (59 stops in 107 possessions)

29. Jacksonville 55.0 (61 stops in 111 possessions)

30. Carolina 54.7 (58 stops in 106 possessions)

31. Tennessee 52.8 (56 stops in 106 possessions)

32. Oakland 51.8 (59 stops in 114 possessions)

Biggest gainers this week: Baltimore (up seven spots this week); Buffalo (up four spots this week); Cincinnati (up four spots this week); New York Jets (up four spots this week).

Biggest losers this week: Indianapolis (down six spots this week); Philadelphia (down four spots this week); Jacksonville (down three spots this week)

Average league STOP Factor (through Week 11): 63.2

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