At the top of any screwed by the Bills list has to be James "Shack" Harris. The Bills were brave enough to draft him out of Grambling in 1969, but could never hand over full-time QB'ing to an African American. By the time Lou Saban was hired—who had already screwed over QB Marlon Briscoe in Denver—Harris was shipped out, and ended up a Pro Bowler in LA. There too, he was screwed for reasons as simple as black and white.
I can't help wondering how much better the Bills would have been in 72 and 73, years in which the QB play was abysmal, if they had given a young vet like Harris the keys. Oh, well.
(And yes, I am a Fergy fan...but Fergy in 1973 was nothing but a rookie bus driver handing off to OJ. If the passing game had been more consistent, that team would have gone to the playoffs.)