Stat of the Day: 2009 CB Charting Stats

by Aaron Schatz

As part of our ongoing Stat of the Day series, we're digging deep into our spreadsheets to run a new stat every weekday until Super Bowl XLIV.

We've snuck some cornerback charting numbers into the various playoff previews, but today we'll take a wholesale look at the top corners of 2009 based on our game charting data so far. I've ranked all cornerbacks with at least 40 charted passes, which means 70 total cornerbacks. I've removed passes marked as Hail Mary, Hit in Motion, Tipped at Line, or Thrown Away. I've also removed wide receiver screens, which aren't really a good way to measure cornerback coverage because a cornerback in man coverage is going to (or at least, is supposed to) immediately get blocked out of the play by another wide receiver. Right now I'm only looking at primary defenders, so this is not adjusted to account for double coverage, or plays where the charter marks a hole in zone but lists an appropriate zone defender in the second DEFENDER column. There are no opponent adjustments yet, and pass interference is not yet included.

Typical caveats apply, of course: This is imperfect data based on the game charting project, which means it comes off limited television camera angles. In past years, this data has been very inconsistent from year to year, and we're going to study that in the offseason to try to figure out if we can get more accurate numbers by, say, looking at players over two-year spans.

Success Rate, to remind everyone, is the percentage of passes that don't manage to get at least 45 percent of needed yards on first down, 60 percent of needed yards on second down, or 100 percent of needed yards on third down.

Yes, that list includes three New York Jets. Do you think Rex Ryan's blitz schemes had an effect on that defense? This continues the insane inconsistency of Lito Sheppard [1], who according to five years of game charting data was one of the worst cornerbacks in the league in 2005, 2007, and 2008 but one of the best cornerbacks in the league in 2006 and 2009.

Hey, look who's back from the dead? It's our good friend Leigh Bodden [2]! Welcome back, Leigh! He honestly didn't look this good during the season, subjectively, but the charting data has him rated higher than Shawn Springs and much, much higher than the Patriots' younger cornerbacks.

Drayton Florence? I have no idea what's up there. By the way, you might remember Tarell Brown [3] as number four on our Top 25 Prospects list in Pro Football Prospectus 2008.

A lot of the same players appear on both lists, but we add a couple of Colts, a reminder of the basic strategy of zone coverage: prevent big gains. Speaking of zone coverage and preventing big gains, three Colts appear on our list of the cornerbacks who best prevented yards after catch. (The Colts actually had four different cornerbacks hit the 40 targets minimum, because you face a lot of passes when you are winning and because the Colts are one of only two teams where the whole season is already charted.)

I guess I didn't watch that much Kansas City this year, but did they play primarily zone? It didn't necessarily have to be Cover-2, but having two cornerbacks who barely allow any yards after catch matches the typical blueprint for a zone defense.

After looking at these tables, I would like to apologize to Dominique Rodgers-Cromartie [4] and his fans. We've been saying for a few weeks that DRC was a poor choice for the Pro Bowl, based on our charting numbers. However, as more charting numbers have come in, DRC's numbers have steadily improved. He clearly got better in the second half of the season, especially when it came to allowing big plays. Here are his numbers split in half:

Finally, one more table, in praise of he who shall never make the required minimum to be ranked:

Most of the numbers aren't that special, but that total of charted targets (in 14.5 games we've charted so far) is just ridiculous. Even after adjusting for how many games are still left uncharted, teams threw at Darrelle Revis [5] four times as often as they threw at Nnamdi Asomugha [6].

Tomorrow we'll flip the script and run "10 worst" tables for cornerback charting stats.