Here is an interesting fact that Ray Fittipaldo of the Pittsburgh Post-Gazette just raised: of the six players that the Pittsburgh Steelers previously used a franchise tag on, none of them actually finished their careers in Pittsburgh. In fact, of those that went on to sign a long-term deal, most did not even make it to the end of their contract.
This is a useful perspective to keep in mind while discussing the current situation with Le’Veon Bell, as well as the instability of the concept of a ‘franchise’ player in general.