The other part of our predicament that many (including me) struggle to accept is just how mediocre we are.
I understand, but if you don't want to accept that fact, it's comforting to think that he's a bad manager and swapping him for a better one will make all the mediocrity vanish. But I think it's difficult to find a better manager, if those exist at all. I don't think the idea that Guardiola or Mourinho are better managers has much support in the facts at all. Their suitability to this specific kind of job is even more doubtful.
I can accept it takes time to overtake City and Arsenal to win the league and certainly to build a team to compete with the elite European teams; what I can't justify are cup exits to mediocre teams (PSV and Boro) and struggling to keep pace with West Ham and Leicester. The focus on long-term (if that is what it is) is also contrary to Van Gaal's comments when he joined - then all the talk was about being first and winning trophies (as he managed at Bayern and Barcelona to be fair), not a Moyesian 6 year project where criticism is suspended while the masterpiece is slowly assembled behind the curtain.
To me it's obvious it's not going as expected. Normally after the match at Whiteheart Lane last year, that would be the match that it clicked and it would have been continuous upward curve from there, as the players had learned the basics of the paying style. But somehow they managed to play like they unlearned it, and started dwelling on the ball and playing too slow again. Then after the good run of games in the spring, it again was a bit too slow against Chelsea, allthough they are a good defensive side, but after that they lost it completely agian and failed to finish 2nd. This season again progress has not been steady, to put it mildly, even after a couple of decent games, the FA cup match was a step back again. That's an issue, it would be nice if the squad would consistently start matches at the level they've reached already.
This probably has to do with the particulariteis of the PL and this squad, and the manager is responsible and allways the one to blame. But the question is whether this is a reason to quit the chosen path back to the top. I don't think it is, but more importantly I think it's very dangerous because United might not find another path back to the top at all. If there's no willingness to stay the distance, and quit the path at first big bad run, the question is if the club has what it takes to get back to the top.