Farve needs to gracefully retire with his reputation intact.
Johnny Unitas, one of the great quarterbacks, continued playing way past his prime, ended up leaving the Baltimore Colts for some other team, and ended up having his effigy burned after he threw 3 or more interceptions in one game.
Of course, for many of these guys football (or baseball, or tennis, or even ping pong) is all they have known since grade school. It is their identity. I can see why they do not wish to 'retire' and so lose their identity.