I just finished reading an excellent book titled the The Wages of Wins by David Berri, Martin Schmidt, and Stacey Brook. The authors are three professors of economics, so the statistical analysis is pretty dense and not for everyone. The book discusses why fans don't care about labor disputes, why the NBA teams with the highest salaries don't have the most wins and NBA star players don't help sell tickets to home games, and why competitive balance has never been better in MLB and Bud Selig's Blue Ribbon Panel which found otherwise is wrong.
For the NFL they focused on the quarterback and specifically Brett Favre. They assign a point value to every action that takes place during a game, for example the net impact of an interception is 3.7 points. This is an attempt to create a better measure of a quarterback than the awful NFL quarterback rating. What they discovered when looking at quarterbacks from 1995 to 2004 was that the only thing consistent about them is their inconsistency. They use Favre as an example of this: