Before the season, in "Football Outsiders Almanac 2011," we took a look at the fade of the Atlanta Falcons' run defense down the stretch last year. In Weeks 1-9 of the 2010 season, the Atlanta run defense compiled a DVOA of minus-22.7 percent, which ranked them third in the league. From Week 10 to Week 17, though, the run defense collapsed and allowed a 15.7 percent DVOA -- pushing their year-end rush defense DVOA to minus-4.1 percent, which was good for just 13th overall.
We noted in the Atlanta chapter that a collapse like that doesn't necessarily portend bad things for the future of the unit though, and sure enough, the Falcons run defense has again been stout this season. Their rush defense DVOA of minus-20.3 percent places them third in the league through Week 15, behind only the Bears and 49ers. (For an explanation of Football Outsiders' DVOA metric, read here.)
The main reason for the course correction has been the emergence of 2010 first-round linebacker Sean Weatherspoon. While Weatherspoon showed flashes of talent during his rookie season, a sprained knee left him playing mainly on passing downs after the first month of the season, if he played at all. He didn't get off to the most auspicious start to his second year, getting chewed out by head coach Mike Smith for poor tackling technique in a Week 1 loss to the Bears. But since then, he has taken his game to another level. We measure each defensive player's overall success with a stat called stop rate, which looks at the percentage of a player's plays (tackles or assists) that kept the offense from producing a successful gain on that down. Weatherspoon had a meager 44 percent stop rate in 2010. This season it has risen all the way to 63 percent.