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.
However, it's not just the quality of the plays that Weatherspoon has made that has stood out -- it has been the quantity. Weatherspoon is one of just 13 linebackers this season to have been involved in 16 (or more) percent of his team's plays. Of those 13 players, only Brian Cushing of the Texans has a higher stop rate than Weatherspoon. And an early look at our game charting data has shown him to be solid in pass coverage as well. Among the linebackers who we have 25 targets for so far, Weatherspoon's 4.5 yards per target ranks seventh.
Another of the Atlanta linebackers, Curtis Lofton, has continued to excel at shutting down the running game next to Weatherspoon. Not only is Lofton in that aforementioned group of 13 high-usage linebackers, but out of that group, only Weatherspoon and NaVorro Bowman can boast a better stop rate against the run than Lofton. Combine those two with Atlanta's excellent defensive tackle tandem of Corey Peters and Jonathan Babineaux, and it hasn't been easy to find a crease against Atlanta. In fact, the only two running backs to gain 100 yards against Atlanta so far this season have been Maurice Jones-Drew and Arian Foster.
Unfortunately for the Falcons, their rather ordinary secondary continues to be a problem. Brent Grimes, who has missed some time this season, also comes out very well in our early charting numbers. Among cornerbacks with at least 30 charted passes thrown their way, he ranks ninth in success rate (67 percent) and is tied for 18th in yards per pass allowed (5.9), making him the lone bright spot of the unit.
On the other side, Dunta Robinson has continued to not live up to his enormous contract. He's allowing 9.0 yards per attempt, which ranks in the bottom 15 of all players that have been targeted more than 30 times. The scary thing is, as mediocre as Robinson has been, he's clearly the second-best pass defender in the secondary. Safeties Thomas DeCoud and William Moore have continued to make mental mistakes, and veteran James Sanders is definitely more of a run-stuffer at this point in his career. Aside from Grimes, only two members of the Falcons secondary have allowed fewer than the 9.0 yards per attempt that Robinson has, per the charting project. Those two are Kelvin Hayden, who has missed the last month with a dislocated toe, and Dominique Franks, who we have only four charted targets against so far.
So while the Atlanta run defense is more than up for the challenge of taking on the Saints, their pass defense continues to need improvements. The hope this offseason was that the big-money signing of Ray Edwards would help tip the scales by providing extra pressure on opposing quarterbacks. Instead, Atlanta's adjusted sack rate has stalled out at 6.2 percent, just 0.3 percent better than in 2010. Edwards has added only three additional quarterback hits to his four sacks, which means that despite much less playing time, backup lineman Kroy Biermann has just one fewer quarterback knockdown than Edwards on the season.
It's a testament to the skills of Weatherspoon and Grimes that this unit has played as well as it has against the pass. It's up to Thomas Dimitroff to conjure up the additional talent in the secondary that this team needs to be a complete defense -- a task that will be much harder without the draft picks sent to Cleveland in next year's draft to complete the Julio Jones trade.
Rivers McCown is an assistant editor for Football Outsiders. You can follow him on Twitter here.