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How Good was Revis in 2009?

Bill Barnwell, of Football Outsides,  recently spoke with the New York Times blog Freakonomics to talk football. One of the questions that came was about none other than Darrelle Revis.

Q. How valuable (in wins, and therefore is dollars) is Darelle Revis?

The salary average and variance varies by position. So too does the impact on the game. Which positions are overpaid and underpaid relative to the average or variance?

How well can you isolate the play of any particular player (e.g., the RB) from that of his teammates (e.g., the O-line)? Who contributes more to a 2000-yard season, the RB or the line? — Erik

A. By the statistics we do have, though, Darrelle Revis was quite the cornerback in 2009. Our Game Charting Project at Football Outsiders uses a flotilla of volunteers to track a variety of things that aren’t contained in the official NFL play-by-play, like how many blitzers there were on a given pass play, whether there was play-action, or whether a defender rushed the quarterback into a throw.  For pass plays, we use the angles provided on TV broadcasts to guesstimate who the receiver in coverage was. (For plays where there’s a blown coverage, our charters can list that the catch came in a “Hole in Zone”; or with clear double coverage, they can list more than one defender.) It’s an inexact science, since it’s difficult to diagnose certain coverage schemes from that camera angle, but it’s a big step in the right direction for analyzing the play of defensive backs.

Two of the primary stats we track for cornerbacks are Yards per Attempt (YPA) and Success Rate. YPA is, very simply, the number of yards a receiver gave up divided by the number of times he was in coverage. Success Rate captures the percentage of the time that the offense threw a pass against a particular defender and gained 45 percent of the needed yards for a new set of downs on first down, 60 percent of the needed yards on second down, or 100 percent of the needed yards on third or fourth down. Completions that don’t meet these standards, incompletions, or interceptions are considered to be failures.

Darrelle Revis paced all starting cornerbacks in both YPA and Success Rate in 2009, and it wasn’t particularly close. His YPA was 2.9 standard deviations above the average performance by a qualifying cornerback, while his Success Rate was 3.0 standard deviations above that average corner.

To try and place that in context with more traditional statistics, I noted that Revis was thrown at 96 times, which was the fifth-most targets of any corner in the league. I split the difference between those two Z-scores, suggesting that Revis was playing at a level 2.95 standard deviations above the average starting corner, and then applied that level of performance on a per-play basis to those players that ranked fifth in the league in usage at their particular category.

The results were staggering. Peyton Manning threw the fifth-most passes of any quarterback in the league. He actually threw for 4,640 yards. If he was playing at a level 2.95 standard deviations above the mean, like Revis was, he would have thrown for 5,532 yards — that would be an NFL record. Maurice Jones-Drew was the running back with the fifth-most carries in the league. While he ran for 1,391 yards, a Revis-style performance would have seen him hit exactly 2,000 yards. Brandon Marshall picked up 1,127 receiving yards while finishing fifth in the league in catches; had he been 2.95 standard deviations above the mean on a per-play basis, he would’ve picked up 1,922 receiving yards, which would also have been a league record.

Placing a value on that sort of performance is another topic altogether, but I think it’s pretty clear that Darrelle Revis spent his 2009 season playing at a truly remarkable level.

Wow, those are some pretty staggering statistics. I still can’t believe Revis didn’t win defensive players of the year. I admit I’m biased, but still. How can you say with a straight face that Revis wasn’t the best defensive player in football last season. You can’t. But I digress. Let’s just hope Revis and his people don’t get their hands on these stats or else they might be asking for $20 million per season.


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