Nope, I don't think it was anything close to that.
He could have left at the end if his last full season and been a strong candidate for the Rangers job. It seems pretty clear he stayed on one more season (one season too long as it turned out) because he wanted a run at some silverware. That ended prematurely, even by our standards, and then I think him, and the rest of the team, ended up somewhat demotivated.
The bad luck with injuries played a part too, but can't really complain too much as we had good luck the seasons we were best of the rest.
In a couple of interviews, he also sounded genuinely pissed off that Baraclough was given access to a lot more resources under the new owner that he was denied in the first half of the season.