I'm not throwing darts at the Bills for this one. Unlike the hindsight savants here.
In Peters mind he was a great. But it was far from known to management that Peters would become a sustained great. When the Eagles made an offer that couldn't be refused, the Bills took it.
Opinion, I think Peters had a woody to leave Buffalo, no offer was going to be good enough. And I do remember what others posted: his season ending injuries that happened when the playoff run was over.