If results aren't great and the team isn't performing to its potential? Absolutely.
In those circumstances they'd be sacking him because of the results and the quality of the football, which are perfectly legitimate reasons to dispense with your manager. The precedent that sets is a good one - if you (the manager) fail to win games or subject us all to having to watch shite football for years, you'll be out on your arse.If the team were playing shite for 2 seasons yes.
That's quite different from sacking the manager because some individual in his squad doesn't like him and keeps telling the world about it. The message that sends is completely wrong and will make the next manager's job nigh impossible.