AdamJT13
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I've said for a while that ESPN.com's K.C. Joyner is useful for compiling statistics but doesn't always know quite how to put them to good use. For example, his cornerback "metrics" focus on the plays when a cornerback is targeted but give no credit to cornerbacks whom opponents avoid. So if the 2007 Cowboys had a game when Jacques Reeves was targeted 12 times and allowed seven catches for 81 yards, Anthony Henry was targeted six times and allowed three catches for 42 yards and Terence Newman was targeted once and allowed one catch for 8 yards, Joyner's "metrics" (YPA and SYPA) would say that Reeves performed the best and Newman performed the worst, even if they all played the same number of snaps -- or even if Reeves played the least and Newman played the most.
Clearly, though, cornerbacks have to be given credit for covering so well that opponents avoid throwing at them. One way to do this is to look at the number of yards allowed compared to the number of passes faced -- regardless of whether that cornerback was targeted. If a cornerback is on the field for 50 passes in a game, that's 50 times when the opponent could target him. If he was targeted four times and allowed two catches for 25 yards, he almost certainly performed better than if he had been targeted 16 times and allowed eight catches for 100 yards -- even though Joyner's "metrics" would say that the performances were exactly equal.
What I've done for the past few seasons is to take the raw cornerback stats compiled by Joyner (and STATS and Football Outsiders) and compare them to each player's estimated pass attempts faced, which is determined by their official playing time percentage and their team's opponents' passing attempts. The result is statistics such as each cornerback's target percentage (how frequently they were targeted when they were on the field), their "bad play" percentage (how frequently they allowed a catch or were penalized) and their yards allowed per pass attempt (not per target).
To me, the top "shutdown" cornerbacks are the guys who allow the fewest yards per pass attempt that they play. Simply looking at total yards allowed -- even for cornerbacks who play every snap of the season -- could be deceiving because one team could face fewer than 450 pass attempts, while another team could face more than 600. And if a cornerback plays 90 percent of his team's defensive snaps instead of 100 percent, that could cut his number of attempts faced by about 60 -- roughly two games' worth.
The top "shutdown" cornerbacks each season typically allow fewer than 1.0 yards per pass attempt played -- ie., fewer than 500 yards allowed on 500 pass attempts faced, or fewer than 600 yards on 600 attempts, etc. Starting last season, K.C. Joyner started counting only the targets, catches and yards when a cornerback was in "direct coverage," which results in smaller numbers for every player and especially smaller numbers for teams that play primarily zone schemes such as the Tampa 2. (The discrepancies between Joyner's "direct coverage" numbers and the totals kept by Football Outsiders and STATS typically are greater for those teams than for other teams.) Joyner also combines catches and defensive penalties to a get a total number of unsuccessful plays, combines receiving yards and net penalty yards for a total number of yards allowed and combines attempts and penalties (but not spikes) to get the number of passes against each team.
In 2007, based on Joyner's numbers and adjusted for each player's playing time and estimated pass attempts faced, 17 of the 81 cornerbacks who started at least five games allowed fewer than 1.0 yards per estimated pass play faced. The top 10 all allowed 0.93 or less. There were four who allowed 2.0 or more, and the bottom 10 all allowed 1.69 or more.
Here are the top "shutdown" cornerbacks of 2007, based on net yards allowed per estimated pass faced --
1. Ronde Barber 0.535
2. Marlin Jackson 0.618
3. Nnamdi Asomugha 0.638
4. Terence Newman 0.818
5. Charles Tillman 0.902
6. Fred Bennett 0.908
7. Will Allen 0.909
8. Carlos Rogers 0.913
9. Deshea Townsend 0.921
10. Travis Fisher 0.930
I suspect that Barber and Jackson benefitted somewhat from their teams' zone defensive schemes, which lower the number of times Joyner determines that they're in "direct coverage," as well as the length of the passes they're defending. I'll see what Football Outsiders says they allowed when their book arrives in the next week or so. (I'm still trying to get STATS' numbers from 2007.)
Here were the bottom 10 "shutdown" cornerbacks for 2007 --
72. David Barrett 1.689
73. Ike Taylor 1.737
74. Corey Ivy 1.759
75. William James 1.832
76. Chris Houston 1.901
77. Demarcus Faggins 1.925
78. Travis Daniels 2.022
79. Lewis Sanders 2.030
80. Stanley Wilson 2.144
81. Jason David 2.562
If you're wondering, Anthony Henry ranked 44th (1.285), and Jacques Reeves ranked 69th (1.632).
Some other notable cornerbacks -- Charles Woodson 12th (0.959), Shawn Springs 18th (1.000), DeAngelo Hall 21st (1.016), Champ Bailey 28th (1.115), Asante Samuel 31st (1.14), Sheldon Brown 33rd (1.147), Marcus Trufant 38th (1.212), Al Harris 49th (1.378) and Lito Sheppard 67th (1.601).
While Jacques Reeves was nicknamed "The Human Target" by Football Outsiders because of his overall target percentage, Joyner's numbers show that several other players were targeted a higher percentage of the time that they were on the field. Reeves was targeted on 20.6 percent of his estimated pass plays faced, which ranked 75th (seventh-worst) out of 81. The highest target percentage was Fakhir Brown's 21.7 percent. Lito Sheppard and Anthony Henry both finished just outside the bottom 10, at 19.7 percent and 19.5 percent, respectively. Marcus Trufant had the most total targets, 111, and was 67th in target percentage (19.1).
The lowest target percentages belonged to Marlin Jackson (8.7), Nnamdi Asomugha (9.1) and Ronde Barber (10.9). Again, I suspect that Jackson's and Barber's coverage schemes and Joyner's "direct coverage" standards lowered their numbers. Newman finished with the 13th-lowest target percentage, 13.5 percent.
Some other notes about Joyner's numbers adjusted for playing time and attempts --
-- Newman allowed only 9.8 yards per catch/defensive penalty, which was the fourth-best. As noted above, his yards allowed per estimated pass play also was the fourth-best, at 0.818. So even with injuries all season, he still was one of the top shutdown cornerbacks in the league. In Joyner's main metric, yards allowed per target (he calls it YPA), Newman was ninth-best (6.07). In SYPA (success percentage times yards per target), Newman was 22nd, which is still quite good, but he gets dragged down by his success percentage (a below-average 62.1). Whether it was because of his foot injuries or Wade Phillips' softer coverages, Newman was targeted a little more (not much, as he still was 13th-best in target percentage) and allowed a higher percentage of successful short passes than he typically does. But the overall result was yet another "shutdown" season for Newman.
-- Asomugha had by far the lowest "unsuccessful play" ratio, with one catch or defensive penalty every 29.4 pass attempts he faced (the next-best was 17.7). But he had one of the highest yards allowed per unsuccessful play -- 18.8, which ranked 79th out of 81. So he was almost never targeted or beaten, but when he was beaten, he often gave up big chunks of yardage.
-- Carlos Rogers played only seven games but put up some good numbers (eighth-best in yards allowed per estimated pass play). Like Asomugha, he also gave up some big chunks of yardage when he was beaten -- he was 75th in yards allowed per catch/defensive penalty (16.2).
Of course, none of these stats should be considered precise, as Joyner's numbers are subjective and will differ from those compiled by Football Outsiders and STATS, and the number of pass plays faced is merely an estimate based on the team's total and the player's playing time percentage. And as with any stats, each player's numbers are at least partly affected by his assignments, his teammates, the quality of his opponents, etc. But I think they're a pretty good start for making better use of Joyner's numbers than what he does with them.
Clearly, though, cornerbacks have to be given credit for covering so well that opponents avoid throwing at them. One way to do this is to look at the number of yards allowed compared to the number of passes faced -- regardless of whether that cornerback was targeted. If a cornerback is on the field for 50 passes in a game, that's 50 times when the opponent could target him. If he was targeted four times and allowed two catches for 25 yards, he almost certainly performed better than if he had been targeted 16 times and allowed eight catches for 100 yards -- even though Joyner's "metrics" would say that the performances were exactly equal.
What I've done for the past few seasons is to take the raw cornerback stats compiled by Joyner (and STATS and Football Outsiders) and compare them to each player's estimated pass attempts faced, which is determined by their official playing time percentage and their team's opponents' passing attempts. The result is statistics such as each cornerback's target percentage (how frequently they were targeted when they were on the field), their "bad play" percentage (how frequently they allowed a catch or were penalized) and their yards allowed per pass attempt (not per target).
To me, the top "shutdown" cornerbacks are the guys who allow the fewest yards per pass attempt that they play. Simply looking at total yards allowed -- even for cornerbacks who play every snap of the season -- could be deceiving because one team could face fewer than 450 pass attempts, while another team could face more than 600. And if a cornerback plays 90 percent of his team's defensive snaps instead of 100 percent, that could cut his number of attempts faced by about 60 -- roughly two games' worth.
The top "shutdown" cornerbacks each season typically allow fewer than 1.0 yards per pass attempt played -- ie., fewer than 500 yards allowed on 500 pass attempts faced, or fewer than 600 yards on 600 attempts, etc. Starting last season, K.C. Joyner started counting only the targets, catches and yards when a cornerback was in "direct coverage," which results in smaller numbers for every player and especially smaller numbers for teams that play primarily zone schemes such as the Tampa 2. (The discrepancies between Joyner's "direct coverage" numbers and the totals kept by Football Outsiders and STATS typically are greater for those teams than for other teams.) Joyner also combines catches and defensive penalties to a get a total number of unsuccessful plays, combines receiving yards and net penalty yards for a total number of yards allowed and combines attempts and penalties (but not spikes) to get the number of passes against each team.
In 2007, based on Joyner's numbers and adjusted for each player's playing time and estimated pass attempts faced, 17 of the 81 cornerbacks who started at least five games allowed fewer than 1.0 yards per estimated pass play faced. The top 10 all allowed 0.93 or less. There were four who allowed 2.0 or more, and the bottom 10 all allowed 1.69 or more.
Here are the top "shutdown" cornerbacks of 2007, based on net yards allowed per estimated pass faced --
1. Ronde Barber 0.535
2. Marlin Jackson 0.618
3. Nnamdi Asomugha 0.638
4. Terence Newman 0.818
5. Charles Tillman 0.902
6. Fred Bennett 0.908
7. Will Allen 0.909
8. Carlos Rogers 0.913
9. Deshea Townsend 0.921
10. Travis Fisher 0.930
I suspect that Barber and Jackson benefitted somewhat from their teams' zone defensive schemes, which lower the number of times Joyner determines that they're in "direct coverage," as well as the length of the passes they're defending. I'll see what Football Outsiders says they allowed when their book arrives in the next week or so. (I'm still trying to get STATS' numbers from 2007.)
Here were the bottom 10 "shutdown" cornerbacks for 2007 --
72. David Barrett 1.689
73. Ike Taylor 1.737
74. Corey Ivy 1.759
75. William James 1.832
76. Chris Houston 1.901
77. Demarcus Faggins 1.925
78. Travis Daniels 2.022
79. Lewis Sanders 2.030
80. Stanley Wilson 2.144
81. Jason David 2.562
If you're wondering, Anthony Henry ranked 44th (1.285), and Jacques Reeves ranked 69th (1.632).
Some other notable cornerbacks -- Charles Woodson 12th (0.959), Shawn Springs 18th (1.000), DeAngelo Hall 21st (1.016), Champ Bailey 28th (1.115), Asante Samuel 31st (1.14), Sheldon Brown 33rd (1.147), Marcus Trufant 38th (1.212), Al Harris 49th (1.378) and Lito Sheppard 67th (1.601).
While Jacques Reeves was nicknamed "The Human Target" by Football Outsiders because of his overall target percentage, Joyner's numbers show that several other players were targeted a higher percentage of the time that they were on the field. Reeves was targeted on 20.6 percent of his estimated pass plays faced, which ranked 75th (seventh-worst) out of 81. The highest target percentage was Fakhir Brown's 21.7 percent. Lito Sheppard and Anthony Henry both finished just outside the bottom 10, at 19.7 percent and 19.5 percent, respectively. Marcus Trufant had the most total targets, 111, and was 67th in target percentage (19.1).
The lowest target percentages belonged to Marlin Jackson (8.7), Nnamdi Asomugha (9.1) and Ronde Barber (10.9). Again, I suspect that Jackson's and Barber's coverage schemes and Joyner's "direct coverage" standards lowered their numbers. Newman finished with the 13th-lowest target percentage, 13.5 percent.
Some other notes about Joyner's numbers adjusted for playing time and attempts --
-- Newman allowed only 9.8 yards per catch/defensive penalty, which was the fourth-best. As noted above, his yards allowed per estimated pass play also was the fourth-best, at 0.818. So even with injuries all season, he still was one of the top shutdown cornerbacks in the league. In Joyner's main metric, yards allowed per target (he calls it YPA), Newman was ninth-best (6.07). In SYPA (success percentage times yards per target), Newman was 22nd, which is still quite good, but he gets dragged down by his success percentage (a below-average 62.1). Whether it was because of his foot injuries or Wade Phillips' softer coverages, Newman was targeted a little more (not much, as he still was 13th-best in target percentage) and allowed a higher percentage of successful short passes than he typically does. But the overall result was yet another "shutdown" season for Newman.
-- Asomugha had by far the lowest "unsuccessful play" ratio, with one catch or defensive penalty every 29.4 pass attempts he faced (the next-best was 17.7). But he had one of the highest yards allowed per unsuccessful play -- 18.8, which ranked 79th out of 81. So he was almost never targeted or beaten, but when he was beaten, he often gave up big chunks of yardage.
-- Carlos Rogers played only seven games but put up some good numbers (eighth-best in yards allowed per estimated pass play). Like Asomugha, he also gave up some big chunks of yardage when he was beaten -- he was 75th in yards allowed per catch/defensive penalty (16.2).
Of course, none of these stats should be considered precise, as Joyner's numbers are subjective and will differ from those compiled by Football Outsiders and STATS, and the number of pass plays faced is merely an estimate based on the team's total and the player's playing time percentage. And as with any stats, each player's numbers are at least partly affected by his assignments, his teammates, the quality of his opponents, etc. But I think they're a pretty good start for making better use of Joyner's numbers than what he does with them.
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