This isn't really easy, add Brian Sipe (Browns) and Steve Grogan (Patriots) to the list. Most teams don't keep their QBs forever unless they are successful. Also even elite QBs play a few years past their prime after the team that drafted them lets them go.
Lots in the old days when teams were "clubs" and they played for the fun. Today its all about the money. An elite past his prime can still draw in a few million. Remember back in the day those players had other jobs to help pay the bills and put food on the table.
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