of career, so you get a lot of credit for just hanging around for a long time. The career data is greatly skewed to favor QBs who played most or all of their careers this century, when the NFL's protection of QBs increased dramatically, and careers have been greatly lengthened as a result. QBs from earlier eras played a much more violent game, with rules that didn't protect QBs nearly as much, and they therefore had shorter careers. If trying to determine the best or greatest QBs across eras, I think it's more relevant to look at TD%, YPA, QB rating, etc.