View Full Version : Interesting Statistic-- Pass Stop Rate-- KC No. 16

08-13-2006, 09:46 AM
Ranking the defensive backs, team-by-team

Interceptions are important, but they hardly tell the whole story about defensive ability. Few defensive backs have more than a sack or two per season. And tackles tell the reader absolutely nothing. Erik Coleman of the New York Jets led defensive backs in tackles in 2005. What exactly does that tell us? Who did he tackle? Was he making tackles five yards downfield, or 15? Did he blow the coverage and tackle the receiver that beat him, or was he cleaning up after one of Justin Miller's mistakes?

Football Outsiders embarked on a data gathering mission at the start of last season intended to capture, among other things, a clear picture of the secondary unit. With a squadron of volunteers, we watched each game (Weeks 1-16) and recorded items that the traditional play-by-play does not cover.

In particular, the charters attempted to mark the defender responsible for each pass regardless of whether the pass was complete or not. Broadcast angles, zone coverages and subjectivity mean the data is hardly infallible, but it is still one of the most comprehensive statistical measures for secondary units out there.

We took those stats as well as our measures of defense against the run, and added a dollop of subjective opinion about off-season changes and player development. The end result is Football Outsiders' unit-by-unit rankings of the best secondaries. (For the full charting data for all 32 secondaries, check out our new book Pro Football Prospectus 2006, in stores now.)

An explanation of the stats: We divide plays into successful plays and non-successful plays. Stops are plays that prevent successful plays. To qualify as a "Stop," a play must keep the offense from gaining 45 percent of needed yards on first down, 60 percent on second down, or 100 percent on third down. Stop Rate is the percentage of a defender's plays that are actually Stops.

When we're talking about Pass Stop Rate, we're talking about our game charting data, which means we're measuring every pass where the defender was in coverage, not necessarily plays where he made an interception or tackle. We also mention Completion Rate, which is slightly different because a complete pass can be a successful play for example, if the cornerback tackles the receiver for a seven-yard gain on third-and-10. Finally, we refer to Deflections (a.k.a. "passes defensed). Charters recorded a deflection when a defender not only tipped the ball, but also when he made a hit that jarred the ball loose. A defender that steps in front of a pass for an interception is also credited with a deflection.

Finally, for teams we use our usual metric DVOA, Defense-adjusted Value Over Average, which takes every single play during the season and compares it to the league average based on situation and opponent, rewarding players for strong performance on third down and in the red zone. We measure DVOA not only for total pass defense, but against specific types of receivers (i.e. number one receivers, or tight ends) and all those numbers for 2005 are found here.

1. Denver
2. Cincinnati
3. Chicago
4. Tampa Bay
5. Dallas
6. Pittsburgh
7. Washington
8. Carolina
9. Philadelphia
10. Baltimore
11. Cleveland
12. Green Bay
13. New England
14. Indianapolis
15. Minnesota

16. Kansas City

Patrick Surtain is an excellent corner, but like Al Harris in Green Bay, he can't do it alone. Surtain allowed a 52 percent completion rate; the other defensive backs, Benny Sapp, Dexter McLeon and the now-departed Warfield, combined to allow a 62 percent completion rate. Ty Law is no longer playing at a Pro Bowl level despite leading the league in interceptions, he finished 80th in Stop Rate but he's way better than anyone else who could fill the slot opposite Surtain. Sapp, Julian Battle and rookie Marcus Maxey will provide the Chiefs with depth at the position.

At safety, Sammy Knight is better known for his skills against run rather than the pass, but has acceptable coverage abilities. Greg Wesley will likely start at free safety, but is the weakest link among the starters and one of the reasons that Kansas City ranked poorly defending passes to tight ends and running backs. Second-round pick Bernard Pollard is a physical player in the mold of Knight, and has skills to be a future starter.

17. Jacksonvillle
18. Atlanta
19. Detroit
20. Buffalo
21. Seattle
22. New York Giants
23. Tennessee
24. Arizona
25. New Orleans
26. Miami
27. New York Jets
28. San Francisco
29. Houston
30. Oakland
31. St. Louis
32. San Diego


08-13-2006, 09:51 AM
Then pull Wesley and put in Pollard..

08-13-2006, 09:56 AM
Then pull Wesley and put in Pollard..

Wesley would have to be replaced by Page.

Which could happen just as easily.