I'm trying to put myself in these coaches' position...knowing you've had it working at a particular school, the job is too demanding...but one last enormous game left to play.
Before the final game, do you pretend to the players you've coached all season that everything's great, see you next season? I'm guessing quite a few players are sharp enough to know when a coach means what he says verses when he is sleep-walking through the motions.
Would the coach with plans to leave put his best effort into that final game? Who knows, but when the dishonest coach winds up taking shots at his former coach that clears things up, in my opinion.