An adjusted view of Mason Crosby's career
March, 5, 2013
By Kevin Seifert | ESPN.com
Jonathan Daniel/Getty ImagesThanks in part to the difficulty of kicking at Lambeau Field, the Packers have stuck by Mason Crosby.When place-kicker Mason Crosby hit a rough patch in 2009, the Green Bay Packers' support never wavered. When he fell into a midseason slump during the 2012 season, the Packers remained patient. As fans wrung their hands and media members warned of dire consequences, there was no evidence the Packers ever considered a move.
Why not? And why have there been no reports of the team making the position an offseason priority for upgrade? After all, Crosby's career conversion rate of 76.8 percent ranks 46th among qualified place-kickers since the start of his career.
I guess we can't rule out the possibility the Packers will seek competition for Crosby this offseason. Assuming they don't, however, I've stumbled across a study that provides a level of quantitative explanation for their continued loyalty.
NFC West blogger/Inside Slant collaborator Mike Sando brought to my attention this MIT research paper presented at last week's MIT Sloan Sports Analytics Conference in Boston. There is a lot of high-level math involved, but in essence the paper's authors -- Torin K. Clark, Aaron W. Johnson and Alexander J. Stimpson -- developed a way to remove the vacuum from evaluating place-kickers.
Their model, explained in the link, weighs each attempt based on its level of difficulty. Distance, weather, environment, altitude and other factors are included. When you run Crosby's career through the model, he qualifies as one of the NFL's most underrated place-kickers of the past decade -- due partly to a high number of 50-plus yard attempts as well as the documented difficulty of kicking at Lambeau Field.
From the paper:
"One of the main metrics used to evaluate and compare kickers is their overall field goal make percentage. This statistic is based on the assumption that better kickers make a higher percentage of their field goal attempts. What this statistic misses, however, is that not all field goal attempts are created equal. Some analyses will account for make percentage at different distances, but as our model shows, not even all field goal attempts of the same distance are created equal. The likelihood that a field goal attempt will be successful, as indicated by our model, is related to the attempt difficulty. A higher likelihood of success means a lower difficulty, and vice versa. By evaluating kicker accounting for the difficulty of their attempts, we can get an unbiased perspective on the kicker's skill."
The first chart shows that since Crosby entered the NFL in 2007, he has attempted more 50-plus yard field goals than every place-kicker except the Oakland Raiders' Sebastian Janikowski. He has missed 19 of those 33 attempts, accounting for nearly half of the total misses in his career.
The second chart, courtesy the MIT paper, is a ranking of the most difficult stadiums to kick in since the start of the 2000 season. The researchers sought to predict the difficulty of a 45-yard attempt -- "the distance where the effect of environmental factors is approximately greatest," in their words -- at every NFL stadium.
Based on kicking results from 3,410 games at 51 stadiums over that time period, the researchers found that Lambeau Field posed a more difficult challenge than every stadium except one: the New England Patriots' Gillette Stadium when it had a grass surface. (The conversion to artificial turf came in 2006.) Based on this model, at least, Lambeau is the most difficult active stadium to kick in.
Crosby, of course, has played half of his 96 career games at Lambeau.
Taken together, the researchers credited Crosby as the fifth-most underrated placekicker in the NFL since 2000. The total level of difficulty of his kicks, they argued, created the fifth-largest gap between his actual conversion rate and his adjusted level-of-difficulty rate.
Obviously, this paper is but one strategy for evaluating place-kickers. The revelations don't excuse Crosby from last year's extended slump, which included 10 misses in a 22-attempt stretch, including two from under 40 yards.
But I do think it helps explain why the Packers are loath to part ways with him. Even if they are not using the same kind of statistical analysis, the Packers know they have asked Crosby to attempt a high number of difficult field goals. And while some of Lambeau's recent history came before the 2007 conversion to hybrid grass-turf field, I think we can all agree that conditions play a significant role there.
Again, the Packers could turn around tomorrow and sign a new place-kicker. Or they could draft one in April. But if you're wondering why that hasn't happened already, I think this MIT paper gives us a better understanding. Expecting better success from another place-kicker would require a better candidate than we might have realized.