Saturday, January 19, 2008

Season in Review:
Sacks & Yards Allowed per Catch

In a recent posting we wondered whether or not the rather precipitous drop in sacks (from 2006 to 2007) by the Steelers' defense might be connected to a change in offensive scheming. Specifically we wondered whether offenses were going to a short(er) passing game to offset the Steelers' ferocious pass rush. As in most things, the results of our query were interesting if not conclusive.

First, here are the raw numbers -- the average yardage allowed per pass attempt by the Steelers' defense versus the median for all NFL defenses:

NFL Median5.905.905.905.806.105.806.006.10

That the Steelers are doing better than most is underscored by this fact: the Steelers 4.90 yards allowed per catch in 2007 is the second lowest figure in the last eight years (Tennessee gave up 4.7 yards per catch in 2000, and three other teams have given up 4.9 yards per catch over the course of a season -- Baltimore 2003, New England 2003, and Chicago 2005).

But of course the question is whether or not there is a relationship between sacks and average yards per catch. For that we'll turn to a couple of graphical representations. First, here is a look at average yards per catch allowed by the Steelers:

And now, here's a graphical look at sacks:

Other than the 2006 season there's seems to be a positive relationship between these two variables. It must be pointed out however that using the miracle that is Microsoft Excel to calculate a correlation coefficient results in a weak (nearly non-existent), positive relationship (.00525).

So while it's hardly conclusive that drop in sacks this past season was the result of shorter passes by opponents, it's something approximating an explanation; and for us that's good enough.

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