Eric Murray and the Limitations of Football Statistics

There is only 31 days left until Gopher Football begins. Eric Murray wears number 31 for the Maroon and Gold. Murray, a senior from Milwaukee, has been the starting boundary cornerback since his sophomore season. He is an unquestioned star with high NFL draft potential. While Gopher fans and NFL scouts know of Murray's value, media accolades have been less frequent. Some of that is probably due to personality. Unlike Briean Boddy-Calhoun, Murray is somewhat reticent to speak. Coach Kill noted that "He's not a guy that says a whole lot, when he does, people listen."

The other reason that Murray gets less spotlight is because of a single number: 1. As in the number of interceptions he's had in his career. Murray admittedly could have more interceptions, but his low number highlights a fundamental problem in how we currently talk about football statistics. How do you evaluate a defensive player who does not seem to be "doing" much? So much discourse on cornerbacks focuses on their interceptions and not their other responsibilities. Murray has many tackles, excels at special teams, and frequently does that while left on an island to play press-man coverage. Yet since he has only one interception, he receives less coverage than his defensive back mates.

One way to evaluate how good of a cornerback Murray might be to look at the number of targets vs the completion rate. If quarterbacks targeted Murray 100 times, but only completed 40% of their passes, then Murray must be a good DB. However, while an improvement over current counting statistics and is itself difficult to find, I'm not sure that this tells us tremendously more than current statistics. It is a post-hoc measurement, not a causal connection. Perhaps then, it's time for another approach.

Spatial Data and Football

Defense is fundamentally difficult to measure. Do you give most of the credit for a broken up pass play to the cornerback who broke up the pass, the defensive lineman who hurried the quarterback, or perhaps the quarterback for throwing the ball to begin with. All of them?

Furthermore, depending on the scheme, there may be deliberate "acceptable" offensive spots. Minnesota under Claeys frequently plays in Quarter coverage, and Claeys's philosophy places a premium on not giving up the run or big plays means that the Gophers will frequently accept short and intermediate throws as risks in their defense.

Murray shines by preventing quarterbacks from considering throwing to his man on passing plays, and crashing in running plays. Jay Sawvel noted "He's a good tackler, he's a great blitzer, he's a tremendous special-teams player, he's very, very good in press coverage to the point where a lot of times a play will just break down. There are a lot of times that he doesn't show up in a play, but he's a big part of our success in it because of what he does for us in the style of football we play."

As football is played on a rectangle we should be able to figure out why certain players are successful. Football is a question of geometry and basic arithmetic. Every strategy is at its core designed to make sure your team a mismatch that can be exploited. On offense, the vanguard is packaging run and pass plays at the same time, and making a decision based on a pre-snap or post-snap read. On defense, it includes a variety of disguises to coverages and blitz packages.

Understanding this in real time is extremely difficult for the average fan, but another sport played on a rectangle has come a long way in this respect. Basketball has embraced the spatial revolution. SportVU cameras have added tremendously to our understanding of defense in basketball. The same kind of evolution is available for football if desired. When coaches talk about play breakdowns and mistakes, they will discuss how a player lined up in the wrong spot or moved the wrong way post snap. Football's next statistical revolution will be finding ways to see these spatial successes and failures quickly, and be able to adjust.

Such an evolution would likely increase Murray's value as a player. His primary skill, the one that scouts and coaches see that casual fans and the media does not, boils down to his consistency in being the right spots. That's what makes him a top NFL prospect, and what makes him part of the best cornerback duo in the conference.