I'd go so far as to say that we wouldn't have finished in 4th, had he stayed until the end of the season, and that's probably the reason why he completely lost it after the Southampton game. He kept us in the race, albeit with a squad that was tailor-made to suit his system. It's, of course, impossible to prove others would have done a better job but I would remind you that some people on here wanted Stellini to take over after then Emirates Marketing Project game.
To put my point across more bluntly, the problem I have with some posts is that, whenever a manager is fired, you read that they intentionally botched the job or that they weren't any good to begin with. In my opinion, it's delusional at best and downright paranoid at worst. I won't even entertain the idea that serial winners like Mourinho or Conte would waste a year of their careers just to... what? Make our lives miserable? Nonsense. The assumption that they're poor managers in the first place relies on the concept that our players, who never won anything, are actually very good but are somehow held back by these incompetent bosses who have won a lot of trophies. Doesn't make much sense either, I think.