This isn't really about achievements or success. I know that most managers who gets sacked usually gets sacked because they are getting bad results, and 99% of the time that is the reason.
However, in this case it was mainly about the fact that if we are seeing manager and owner end up in argument, that could be also a reason in some cases and this is one of those cases. They even argued on the pitch last year for a while, after a match, I don't know if you remember that. So he stayed this long only because he got some good results, but the reality is simple we are not going to see him manage there anymore and he will probably move to a team that will appreciate him a lot more and what he brings to any team he goes to.
What has been flying around is the altercation between the owner of the club and the manager, it's the reason why he was sent away but let's observe somethings for a moment. Don't you think that the owner of the club would have sack him if the manager made the team stay at the top of the league? There maybe other reasons why he was let go but the performance is definitely there, I know Nottingham forest does.well when you don't expect anything from them.
Maybe the new manager will bring luck to the team but it is going to be tough until they get things right. I have not seen any manager that was able to put the team at right place when changes are made after the transfer season has close. The new manager will have some players he will like to sell, now he is gong to be force to used them which is going to affect his performance unless he is allow to make some transfer in the January transfer window.