PFF: The Overrated Sack

I agree that when viewed by itself, number of sacks is a fairly vapid stat. For sabermetrics folks, it's analogous to RBIs in baseball. Lots of situational things go into both of those numbers.

Another way to look at it is that defining the best DE solely by number of sacks is akin to determining the best RB based only upon the number of rushing TDs they have.