Monday, June 27, 2011
Rewind'10: 'Stop Rate' against the pass
By Kevin Seifert
As June winds down into what we hope is a more exciting July, our friends at Football Outsiders continue to offer up unique analysis of your favorite NFC North players. Recently, Aaron Schatz published a number of tables that help us make a dent in the relationship between quality pass defense and tackle numbers.
Vikings cornerback Antoine Winfield was one of the NFL's most effective pass defenders last season.
(Really. I know we've debated this before. At least a few of us. Ok, maybe just me. But it's real and it's a debate so let's fiiiiiiiiiiiiiiiiiight!)
Typically, a cornerback with high tackle totals is associated with poor pass defense. The same goes for linebackers and safeties, to a lesser extent. The idea: Either quarterbacks avoid the best pass defenders, or the best pass defenders prevent more than their share of completions on balls thrown their way.
But that's not always the case, obviously. To that end, Football Outsiders has developed a "Stop Rate," which is the percentage of plays "that prevent a successful play by the offense, defined as 45% of needed yards on first down, 60% of needed yards on second down, and 100% of needed yards on third or fourth down." In other words, a "stop" is a successful defensive play, even if it results in a yardage gain by the offense.
Schatz offers a number of applicable individual marks under this category. The NFC North highlights:
Not surprisingly, Minnesota Vikings cornerback Antoine Winfield, an elite tackler, tied for the NFL lead with 28 stops last season. His Stop Rate of 41 percent ranked No. 5 in the NFL. So even though he had a high number of tackles on passing plays last season (68), it's wrong to call Winfield anything close to a poor pass defender.
On the other hand, Chicago Bears cornerback Charles Tillman had 64 tackles on pass plays last season with only 11 "stops." That gave him a Stop Rate of 17 percent.
Bears nickel man D.J. Moore had 11 stops on 28 tackles against pass plays, a Stop Rate of 38 percent that ranked him No. 6 among NFL cornerbacks. Moore finished tied with Green Bay Packers cornerback Charles Woodson, whose tackling we often overlook. Woodson had 18 stops on 47 tackles against the pass.
Packers safety Charlie Peprah had the best Stop Rate (44 percent) among safeties. Vikings safety Madieu Williams had the ninth-worst (6 percent). Those of us who watched both teams closely last season shouldn't be surprised.
Vikings linebacker Chad Greenway had 61 tackles against the pass last season, second most among NFL linebackers. He had 19 stops for a 31 percent Stop Rate. So there is some, but not much, room to question the quality of Greenway's coverage.
Detroit Lions linebacker DeAndre Levy had the fifth-lowest Stop Rate (24 percent) among NFL linebackers. Levy has consistently appeared on Football Outsiders' highest missed-tackle rate, but I'm not sure these two categories are related.