Thursday, August 26, 2004

X marks the Scott

The FootballOutsiders have an interesting article that tries to quantify how effective NFL cornerbacks are. It's actually a simple model explaining a pretty complicated idea and I think it does a pretty good job. There are some shortcomings (and the author admits as much), but at the very least it's far and away better than any measures you'd find on

Anyway, here's the idea:

Most tackles made by a cornerback come in the passing game after their wide receiver has caught the ball. Unless playing in a deep zone coverage to prevent a first down or touch down, this cornerback has already failed. Which leads to an important assumption for this article: Tackles are a negative statistic for cornerbacks. Interceptions are, of course, a positive statistic. Pass deflections are positive too. And it would be unjust to penalize corners for sacks or tackles for loss. With these assumptions in mind, we can reasonably ascertain what type of statistical profile a good cover corner would possess.

Personally, I prefer to keep such statistical measurements simple. Here's the formula for my Cornerback Coverage Rating (CCR):

(Total tackles- (Tackles for loss + Sacks))/(Interceptions + Pass Deflections)

Interceptions are obviously worth more than pass deflections, but they tend to vary wildly year from year, whereas pass deflections are more consistent. So I arbitrarily decided to value them equally. Good corners should post lower ratings than their less talented colleagues.
I should note, this can only be applied to starting cornerbacks because they're the ones doing the actual covering. Safeties and nickel and dime backs more often find themselves either helping in coverage or playing some form of zone defense (in which case CCR wouldn't apply). Also, the lower the CCR rating, the better the cornerback (ratings range from a league best 1.35 to an awful 17.13).

So what did they find out? For starters, Samari Rolle was the best cornerback in the league with a CCR of 1.35. And guess who was fifth -- Deshea Townsend (2.47). Coming in a close 44th and 57th respectively, were Chad Scott (4.54) and DeWayne Washington (6.06). For reference, only Artrell Hawkins (6.63) and Corey Fuller (6.80) were worse AFC North CBs.

The good news is that Washington is gone. That bad news is that Scott's still around. Luckily, he's resorted to blaming a lot of last season's defensive woes on how Tim Lewis and Willy Robinson mandated that everyone play like robots (as a quick aside, Robinson is now the defensive coordinator in San Fran and the last thing that young team needs is a guy who's unwilling to change with his personnel. That team could very easily win 2 games). Of course, it will be interesting to hear who Scott blames after he gets toasted a few times early in the season.

Either way, the FO article is an interesting approach and at the very least it gives some insight (and support -- but of course I don't think #20 or #30 had many supporters by seasons end) into why Townsend is a much better choice than either Washington or Scott.