Thanks for your replies, guys!
Marcheese: you are right that advanced statistics work best in baseball, as the game can be more easily broken down to individual contributions. I am a big fan of Corsi in hockey also, though. Because to me, hockey can be simplified essentially to goal attempts (aka shots). So measuring shots for vs. shots against for a certain player is useful and perhaps more reliable than other measures like plus/minus.
So, rather than a football analogue of WAR, is there a version of Corsi that would apply to football? Like, is there any way of measuring "scoring chances for vs scoring chances against"? I know this is tough because of how teams switch possession regularly...