Super Bowl Playbook: Getting Into the Secondaries Throughout the week, Mike Tanier will be looking at the Giants and the New England Patriots by the numbers. It is hard to evaluate the performance of a defensive secondary using conventional statistics. Interceptions tell only a small part of the story. Passing yards allowed can be useful, but it is a highly distorted statistic: great teams often allow high passing yard totals while playing prevent defense with a commanding lead, while terrible teams allow fewer yards as opponents run out the clock. Tackle totals by cornerbacks and safeties can be the most misleading numbers of all: a cornerback who records six tackles per game could be a tough tackler, or he could just be dragging down receivers after 15-yard catches that he should have prevented. Tackle totals can be a little more useful, however, if you separate them by type. At Football Outsiders, we classify tackles by defenders according to the yardage allowed and by the down-and-distance situation. A "play" is any tackle, assist, sack, interception or official pass defensed: just about anything a defender can do to crack the stat sheet. A "stop" is a tackle that yields minimal yardage: less than 45 percent of the yardage needed on first down, less than 60 percent of the yardage needed on second down, a tackle short of the markers on third down, or a turnover. That sounds complicated, but the concept is simple: a tackle for a gain of 3 yards on second-and-8 is a "stop." A "defeat" is a tackle for a loss, any play that forces a turnover or a play that prevents a third-down conversion. Finally, we separate passing plays from running plays and keep track of the yardage the offense gained on each play. The resulting data are still not perfect, but the numbers provide a great snapshot of what each defender is doing. Great defensive backs record many stops and defeats. Poor defensive backs, particularly cornerbacks, rack up lots of empty "plays." Safeties have it tough because many of their high-yardage "plays" occur after several of their teammates messed up. This table breaks down the passing plays made by the Giants" top six defensive backs. Name Plays Stops Defeats Yds./Play Antrel Rolle Kenny Phillips Aaron Ross Corey Webster Deon Grant P. Amukamara Corey Webster tied for 13th in the N.F.L. among cornerbacks in defeats; his profile matches those of highly regarded defenders like Brandon Flowers of the Chiefs and Jabari Greer of the Saints. They even match those of Darrelle Revis, who had 55 plays, 24 stops, 12 defeats and 8.3 yards per play. Rolle's profile is also very good; Phillips's yards-per-play average is high because of some clean-up tackles. These are the statistics of an average-to-good secondary. Now, let's look at the Patriots: Devin McCourty Kyle Arrington James Ihedigbo Patrick Chung Antwaun Molden Sergio Brown Julian Edelman The first thing that should leap out from the numbers: the Patriots" starting cornerbacks allow over 13 yards per play, while the Giants cornerbacks combine to average far less than 10 yards per play. The second thing that stands out is the disparity in defeats: the Giants" secondary recorded 45 defeats, the Patriots" 33. Finally, look at Ihedigbo, Molden and Brown. They combined to make a ton of tackles on passing plays, but very few of them were impact tackles. They were running around the field putting out fires after significant gains. What do these numbers tell us? First, they suggest that Corey Webster really deserved a Pro Bowl selection. More important, they illustrate just how leaky the Patriots" secondary is. Even Arrington, the Patriots" best cover corner, can be exploited for lots of 13-yard gains. Ihedigbo and the nickel defenders do their best just to keep plays in front of them. And those low defeat totals show just how easy it is to stay on the field against the Patriots" defense on third down: great news for the Giants, one of the league's best third-down passing teams. Bill Belichick is a master of scheming to protect his secondary, of course. His scheme for most of the season has been to score 38 points and assume his defense can hold the opponent to about 31. The Giants" secondary, while not great, has proven that it is good enough to keep Belichick from using offense as his best defense.