Here's a closer look at the numbers in K.C. Joyner's article, factoring in the amount of time each duo or trio played and the number of passes their opponents threw.
First, here's the combined playing time of each team's listed cornerbacks. If there are two cornerbacks listed and they each played every defensive snap last season, their combined percentage would be 200.00. If there are three players listed, and one played every snap and the other two each played 60 percent of the snaps, their combined percentage would be 220.00.
Code:
[B]COMBINED PLAYING TIME (combined percentage of defensive snaps played) [/B]
1. San Diego -- Antonio Cromartie/Drayton Florence/Quentin Jammer 230.76
2. Cincinnati -- Leon Hall/Johnathan Joseph/Deltha O'Neal 230.00
3. Arizona -- Eric Green/Rod Hood/Antrel Rolle 228.25
[B]4. Dallas -- Anthony Henry/Terence Newman/Jacques Reeves 221.79[/B]
5. Minnesota -- Cedric Griffin/Marcus McCauley/Antoine Winfield 218.40
6. N.Y. Jets -- David Barrett/Hank Poteat/Darrelle Revis 216.98
7. New England -- Ellis Hobbs/Asante Samuel 189.35
8. San Francisco -- Nate Clements/Walt Harris 187.66
9. Denver -- Champ Bailey/Dre' Bly 186.80
10. Seattle -- Kelly Jennings/Marcus Trufant 185.06
11. Pittsburgh -- Ike Taylor/Deshea Townsend 182.58
12. Miami -- Will Allen/Michael Lehan 182.28
13. Tampa Bay -- Ronde Barber/Phillip Buchanon 179.10
14. Tennessee -- Cortland Finnegan/Nick Harper 176.80
15. Indianapolis -- Kelvin Hayden/Marlin Jackson 175.63
16. Buffalo -- Jabari Greer/Terrence McGee 170.16
17. Cleveland -- Leigh Bodden/Eric Wright 169.97
18. Green Bay -- Al Harris/Charles Woodson 169.87
19. Kansas City -- Ty Law/Patrick Surtain 168.18
20. Carolina -- Chris Gamble/Ken Lucas 167.89
21. New Orleans -- Jason David/Mike McKenzie 161.75
22. Houston -- Fred Bennett/DeMarcus Faggins/Dunta Robinson 160.58
23. Oakland -- Nnamdi Asomugha/Stanford Routt 159.57
24. Jacksonville -- Rashean Mathis/Brian Williams 159.28
25. Atlanta -- DeAngelo Hall/Chris Houston 159.25
26. N.Y. Giants -- Sam Madison/Aaron Ross 157.03
27. Philadelphia -- Sheldon Brown/Lito Sheppard 155.01
28. Washington -- Fred Smoot/Shawn Springs 152.86
29. St. Louis -- Ron Bartell/Fakhir Brown 152.23
30. Chicago -- Trumaine McBride/Charles Tillman 147.50
31. Detroit -- Fernando Bryant/Travis Fisher 145.79
32. Baltimore -- Corey Ivy/Chris McAlister 131.78
Obviously, two cornerbacks who were on the field for a combined 131.78 percent of their team's defensive snaps probably would be thrown at fewer times overall than two cornerbacks who were on the field 189.35 percent of the time, and much less than three cornerbacks who were on the field a combined 230.76 percent of the time.
Likewise, even if their playing time is equal, cornerbacks on a team whose opponents throw the ball only 409 times during the season probably will be thrown at much less often that cornerbacks on a team whose opponents attempt 646 passes. So here a the total number of pass attempts for each team's opponents --
Code:
[B]OPPONENTS' PASS ATTEMPTS (regardless of players targeted or cornerbacks' playing time)
[/B]1. Minnesota -- Cedric Griffin/Marcus McCauley/Antoine Winfield 646
2. Detroit -- Fernando Bryant/Travis Fisher 602
3. Washington -- Fred Smoot/Shawn Springs 602
[B]4. Dallas -- Anthony Henry/Terence Newman/Jacques Reeves 581[/B]
5. Cleveland -- Leigh Bodden/Eric Wright 578
6. Arizona -- Eric Green/Rod Hood/Antrel Rolle 570
7. Tennessee -- Cortland Finnegan/Nick Harper 569
8. Seattle -- Kelly Jennings/Marcus Trufant 568
9. Buffalo -- Jabari Greer/Terrence McGee 567
10. San Diego -- Antonio Cromartie/Drayton Florence/Quentin Jammer 555
11. Houston -- Fred Bennett/DeMarcus Faggins/Dunta Robinson 546
12. Jacksonville -- Rashean Mathis/Brian Williams 543
13. San Francisco -- Nate Clements/Walt Harris 543
14. Chicago -- Trumaine McBride/Charles Tillman 541
15. Cincinnati -- Leon Hall/Johnathan Joseph/Deltha O'Neal 540
16. Philadelphia -- Sheldon Brown/Lito Sheppard 539
17. Carolina -- Chris Gamble/Ken Lucas 537
18. Atlanta -- DeAngelo Hall/Chris Houston 536
19. Pittsburgh -- Ike Taylor/Deshea Townsend 536
20. Green Bay -- Al Harris/Charles Woodson 534
21. New England -- Ellis Hobbs/Asante Samuel 526
22. New Orleans -- Jason David/Mike McKenzie 524
23. St. Louis -- Ron Bartell/Fakhir Brown 523
24. N.Y. Giants -- Sam Madison/Aaron Ross 523
25. Indianapolis -- Kelvin Hayden/Marlin Jackson 498
26. Baltimore -- Corey Ivy/Chris McAlister 490
27. Tampa Bay -- Ronde Barber/Phillip Buchanon 490
28. N.Y. Jets -- David Barrett/Hank Poteat/Darrelle Revis 470
29. Kansas City -- Ty Law/Patrick Surtain 462
30. Denver -- Champ Bailey/Dre' Bly 458
31. Oakland -- Nnamdi Asomugha/Stanford Routt 439
32. Miami -- Will Allen/Michael Lehan 409
Using those two numbers, we can estimate the number of passes for which each cornerback was on the field (averaged for each set of cornerbacks). This is only an estimate, because while a player might be on the field for 90 percent of his team's defensive snaps, the ratio of that team's opponents' passes to runs might not be exactly the same for the 10 percent of the plays he missed as it was for the 90 percent when he was on the field.
Generally, teams will face a higher-than-usual percentage of runs when fewer cornerbacks are on the field (short yardage and goal-line situations, for example) and a higher-than-usual percentage of passes when more cornerbacks are on the field (long-yardage situations and against four- or five-wide formations, for example). So in most cases, the actual number of passes might be slightly higher than the estimate, but the margin of error should be about the same for each team, which is all we really care about.
So here are the estimated number of passes faced by each set (average per cornerback listed) --
Code:
[B]ESTIMATED PASSES FOR WHICH EACH CORNERBACK WAS ON THE FIELD (per cornerback listed)
[/B]1. Seattle -- Kelly Jennings/Marcus Trufant 525.57
2. San Francisco -- Nate Clements/Walt Harris 509.50
3. Tennessee -- Cortland Finnegan/Nick Harper 503.00
4. New England -- Ellis Hobbs/Asante Samuel 497.99
5. Cleveland -- Leigh Bodden/Eric Wright 491.21
6. Pittsburgh -- Ike Taylor/Deshea Townsend 489.31
7. Buffalo -- Jabari Greer/Terrence McGee 482.40
8. Minnesota -- Cedric Griffin/Marcus McCauley/Antoine Winfield 470.29
9. Washington -- Fred Smoot/Shawn Springs 460.11
10. Green Bay -- Al Harris/Charles Woodson 453.55
11. Carolina -- Chris Gamble/Ken Lucas 450.78
12. Detroit -- Fernando Bryant/Travis Fisher 438.83
13. Tampa Bay -- Ronde Barber/Phillip Buchanon 438.80
14. Indianapolis -- Kelvin Hayden/Marlin Jackson 437.32
15. Arizona -- Eric Green/Rod Hood/Antrel Rolle 433.68
16. Jacksonville -- Rashean Mathis/Brian Williams 432.45
[B]17. Dallas -- Anthony Henry/Terence Newman/Jacques Reeves 429.53[/B]
18. Denver -- Champ Bailey/Dre' Bly 427.77
19. San Diego -- Antonio Cromartie/Drayton Florence/Quentin Jammer 426.91
20. Atlanta -- DeAngelo Hall/Chris Houston 426.79
21. New Orleans -- Jason David/Mike McKenzie 423.79
22. Philadelphia -- Sheldon Brown/Lito Sheppard 417.75
23. Cincinnati -- Leon Hall/Johnathan Joseph/Deltha O'Neal 414.00
24. N.Y. Giants -- Sam Madison/Aaron Ross 410.63
25. Chicago -- Trumaine McBride/Charles Tillman 398.99
26. St. Louis -- Ron Bartell/Fakhir Brown 398.08
27. Kansas City -- Ty Law/Patrick Surtain 388.50
28. Miami -- Will Allen/Michael Lehan 372.76
29. Oakland -- Nnamdi Asomugha/Stanford Routt 350.26
30. N.Y. Jets -- David Barrett/Hank Poteat/Darrelle Revis 339.94
31. Baltimore -- Corey Ivy/Chris McAlister 322.86
32. Houston -- Fred Bennett/DeMarcus Faggins/Dunta Robinson 292.26
Those first three charts are the raw numbers (or estimates) we can use to try to put Joyner's totals to use. One of the problems with Joyner's "metrics" is that they only take into account the plays on which each cornerback (or each set) was targeted, whether they're targeted a little or a lot. But the frequency of times targeted also can be an indicator of performance. If you're covering the opponent's No. 1 receiver on every play in a game, and the opposing quarterback attempts only one pass in your direction, you probably played a fantastic game -- even if that only attempt was a 12-yard completion (which would give you a HORRIBLE average of 12.0 ypa allowed). On the other hand, if you are thrown at 15 times and allow nine catches for 105 yards in a game, you almost certainly didn't play well, even if your ypa was a respectable 7.0. So it also can be useful to look at the percentage of passes that were directed at cornerbacks. (Football Outsiders dubbed Jacques Reeves "The Human Target" because he had been targeted on a league-high 21 percent of all passes in our games that had been charted through Week 13 last season.)
Using the total number of attempts directed at each set of cornerbacks in Joyner's article, along with our estimated number of pass plays each cornerback was on the field, we can estimate the target percentage per cornerback in each set. If the target percentage is .1667, that means that the average for the cornerbacks in that set is one time targeted for every six passes they were on the field. That might mean one was targeted once every three passes and the other once every 12, but Joyner doesn't break it down by individuals in this article, so we have to use the average for each set.
Because Joyner includes penalties against cornerbacks in their target totals, but those plays aren't included in the estimated number of pass plays, it raises the target percentage slightly. But the effect should be small, and at worst, it can be considered a slight punishment for players who commit a lot of penalties. Besides, this is only an estimate, not a precise figure.
Here's that list of average estimated target percentages --
Code:
[B]ESTIMATED TARGET PERCENTAGE (per listed cornerback) [/B]
1. Indianapolis -- Kelvin Hayden/Marlin Jackson 0.1200
2. Oakland -- Nnamdi Asomugha/Stanford Routt 0.1285
3. Tampa Bay -- Ronde Barber/Phillip Buchanon 0.1322
4. Carolina -- Chris Gamble/Ken Lucas 0.1442
5. Green Bay -- Al Harris/Charles Woodson 0.1444
6. Kansas City -- Ty Law/Patrick Surtain 0.1480
7. Detroit -- Fernando Bryant/Travis Fisher 0.1504
8. Minnesota -- Cedric Griffin/Marcus McCauley/Antoine Winfield 0.1517
9. San Diego -- Antonio Cromartie/Drayton Florence/Quentin Jammer 0.1585
10. N.Y. Giants -- Sam Madison/Aaron Ross 0.1607
11. Jacksonville -- Rashean Mathis/Brian Williams 0.1619
12. Denver -- Champ Bailey/Dre' Bly 0.1625
13. New England -- Ellis Hobbs/Asante Samuel 0.1637
14. Atlanta -- DeAngelo Hall/Chris Houston 0.1640
15. San Francisco -- Nate Clements/Walt Harris 0.1649
16. Chicago -- Trumaine McBride/Charles Tillman 0.1667
17. Tennessee -- Cortland Finnegan/Nick Harper 0.1700
18. Arizona -- Eric Green/Rod Hood/Antrel Rolle 0.1706
19. Washington -- Fred Smoot/Shawn Springs 0.1717
20. Philadelphia -- Sheldon Brown/Lito Sheppard 0.1724
21. Miami -- Will Allen/Michael Lehan 0.1730
22. Buffalo -- Jabari Greer/Terrence McGee 0.1752
23. Houston -- Fred Bennett/DeMarcus Faggins/Dunta Robinson 0.1779
24. St. Louis -- Ron Bartell/Fakhir Brown 0.1784
25. N.Y. Jets -- David Barrett/Hank Poteat/Darrelle Revis 0.1785
[B]26. Dallas -- Anthony Henry/Terence Newman/Jacques Reeves 0.1793[/B]
27. New Orleans -- Jason David/Mike McKenzie 0.1805
28. Cleveland -- Leigh Bodden/Eric Wright 0.1822
29. Baltimore -- Corey Ivy/Chris McAlister 0.1827
30. Pittsburgh -- Ike Taylor/Deshea Townsend 0.1839
31. Cincinnati -- Leon Hall/Johnathan Joseph/Deltha O'Neal 0.1868
32. Seattle -- Kelly Jennings/Marcus Trufant 0.1960
And using the total yards allowed listed by Joyner in the article, we also can estimate the average yards each cornerback in each set allowed per pass play --
Code:
ESTIMATED YARDS ALLOWED PER PASS PLAY (per cornerback listed)
1. Tampa Bay -- Ronde Barber/Phillip Buchanon 0.7646
2. Indianapolis -- Kelvin Hayden/Marlin Jackson 0.8552
3. Washington -- Fred Smoot/Shawn Springs 1.0085
4. Chicago -- Trumaine McBride/Charles Tillman 1.0126
5. Oakland -- Nnamdi Asomugha/Stanford Routt 1.0207
6. Detroit -- Fernando Bryant/Travis Fisher 1.0551
7. Carolina -- Chris Gamble/Ken Lucas 1.0959
8. Miami -- Will Allen/Michael Lehan 1.1160
9. Buffalo -- Jabari Greer/Terrence McGee 1.1235
10. San Diego -- Antonio Cromartie/Drayton Florence/Quentin Jammer 1.2220
11. Green Bay -- Al Harris/Charles Woodson 1.2380
12. Cleveland -- Leigh Bodden/Eric Wright 1.2479
13. San Francisco -- Nate Clements/Walt Harris 1.2561
[B]14. Dallas -- Anthony Henry/Terence Newman/Jacques Reeves 1.2649[/B]
15. Houston -- Fred Bennett/DeMarcus Faggins/Dunta Robinson 1.2672
16. N.Y. Giants -- Sam Madison/Aaron Ross 1.2968
17. Jacksonville -- Rashean Mathis/Brian Williams 1.3273
18. Tennessee -- Cortland Finnegan/Nick Harper 1.3380
19. Arizona -- Eric Green/Rod Hood/Antrel Rolle 1.3382
20. Philadelphia -- Sheldon Brown/Lito Sheppard 1.3393
21. Minnesota -- Cedric Griffin/Marcus McCauley/Antoine Winfield 1.3424
22. Kansas City -- Ty Law/Patrick Surtain 1.3514
23. Seattle -- Kelly Jennings/Marcus Trufant 1.3566
24. Pittsburgh -- Ike Taylor/Deshea Townsend 1.3580
25. Denver -- Champ Bailey/Dre' Bly 1.3582
26. New England -- Ellis Hobbs/Asante Samuel 1.3645
27. Atlanta -- DeAngelo Hall/Chris Houston 1.3754
28. Cincinnati -- Leon Hall/Johnathan Joseph/Deltha O'Neal 1.4163
29. N.Y. Jets -- David Barrett/Hank Poteat/Darrelle Revis 1.4336
30. St. Louis -- Ron Bartell/Fakhir Brown 1.5926
31. Baltimore -- Corey Ivy/Chris McAlister 1.7391
32. New Orleans -- Jason David/Mike McKenzie 1.7827
It's important to remember what I said about Joyner's stats earlier in this thread, that for the past two seasons (2006 and 2007), he has used only "direct coverage" stats for cornerbacks. In the past, he used all types of coverage, then broke it down into "direct" and "indirect." Because he uses only "direct" coverage now, many (not all) attempts directed toward a cornerback's zone or receiver in zone coverage are not included in his stats. That's one reason why the two teams who play the most "Tampa 2" zone defense are so high on the final two rankings (target percentage and yards allowed per estimated pass play). In addition, some zone schemes often keep cornerbacks out of deep coverage against some routes (or at least out of what Joyner would consider "direct coverage"), so that would skew their yards allowed per play (as it would yards per target, which is what Joyner's article used to rank them).
The other thing to keep in mind when looking that the tables above is that including a No. 3 cornerback in the stats usually makes that set of cornerbacks' stats worse. In most cases, those are the third-best cornerbacks on the team, and they typically perform worse than the usual starters. So, in most cases, listing a third cornerback with each set and including their stats will make that set's overall numbers worse -- they'll be targeted a higher percentage of the time and allow more yards per attempt and per completion. And the more that the third-best cornerback plays, the greater the negative effect on that trio's numbers.
Joyner listed three cornerbacks for only six teams -- Dallas, Minnesota, Cincinnati, San Diego, Arizona and the Jets. Here are the playing time percentages for each third-best cornerback -- Dallas (Reeves, 85.17 percent), Minnesota (McCauley, 63.75), Cincinnati (O'Neal, 68.05), San Diego (probably Florence, 79.06), Arizona (Rolle, 66.67) and the Jets (Poteat, 54.1 percent). With Reeves having the highest percentage of playing time of any third cornerback listed AND being one of the most-targeted players in the league (possibly THE most-targeted in the league), it's amazing that our trio still ranked ninth in Joyner's yards allowed per target and 14th in estimated yards allowed per pass play. Football Outsiders had both Newman and Henry among the top-10 cornerbacks in lowest yards allowed per attempt in the games they had charted through Week 13, so we might have been right near the top without Reeves dragging down the averages so much.
Anyhow, it'll be interesting to see how Joyner's numbers stack up against those compiled by Football Outsiders (and STATS LLC, if I can get my hands on their numbers for 2007). Football Outsiders' book is supposed to ship on July 21.