Are Eagles better off keeping veterans?

The recent decision by the Philadelphia Eagles to not extend Donovan McNabb's contract past the 2010 season brought the quarterback's future with the team into question. While the team did guarantee McNabb more money over the next two years, it seems clear the team expects to part ways with McNabb after 2010, at which point he will be 34.

The Eagles' hesitance to re-sign their iconic quarterback is nothing new for the organization. Under the stewardship of Andy Reid, the Eagles' organization has repeatedly been willing to let core veteran players leave once they've passed their prime or can command a salary that the team feels isn't commensurate with their talent level. In this offseason alone, the Eagles declined to re-sign safety Brian Dawkins and offensive tackles Tra Thomas and Jon Runyan. The three had combined for 491 starts and 11 Pro Bowl appearances as Eagles, while Dawkins and Thomas had spent their entire careers with the team.

We won't know if those moves worked out for another year, but what about the previous times that Philadelphia failed to re-sign prominent veterans when they hit the market? We can use Football Outsiders' statistical toolbox to see if losing them really hurt the team.