Fully disagree with that. Mike Shanahan totally screwed Plummer and he had every right to be pissed off at the organization at that time.
Mike Shanahan logic, Jake Plummer leads us to a 13-3 record and and AFC championship game, so let's trade up and draft a QB in 1st rd of the following draft because clearly it's the QB that is the problem with this 13-3 team.
Then Plummer leads us to a 7-4 record the next season, before he promptly get's benched in favor of the rookie QB who then only gets us 2 more wins the rest of the year to miss out on the playoffs. Then Shanny trades him to the worst team in the league for basically nothing and Plummer just said screw it's not worth it, I'll just retire.
Now that Shanny is gone from the fold, Plummer doesn't care about what happened, it's more a vendetta against Shanny than anything. And I really don't blame him. All he did was win and Shanny treated him like horse you know what.