Money doesn't guarantee success, but when you're spending an absolute ton it should be one of the primary metrics by which your performances are judged. Mourinho is exactly where he should be in the league. That's fine...relatively speaking, because it's an improvement on what's come before and it demonstrates an upward trend, but I also don't think it's particularly remarkable for a man who won the CL with Porto, came into the PL, told everyone how great he was and then affirmed that by pissing over United and Arsenal sides that'd dominated for the past decade, and for the guy who's Inter side managed to stop Guardiola's Barca, winning the CL in a year where they essentially beat the best sides from the other three big leagues. Mourinho's been a stabilising influence for us but a lot of the discontent, I think, comes from the fact that we brought him in to be more than that.
While there's obviously a lot that makes United unique, and we're still influenced by the legacy implanted by a historically long-lasting manager, I'd mostly argue we are a normal club...one that'll go through managers who stay for four or five years, ones that stay for a couple, ones that get sacked for not being good enough, and all the rest of it. And Liverpool have demonstrated that you can be out of the top four for a number of years and be relatively okay, so long as you get in someone who improves you again. And quite frankly if we do make a good appointment post-Jose (whenever that may be) then it shouldn't be a problem. Again, longevity and supposed stability is no guarantee of success, because supposed progress can undo itself very, very quickly, as Mourinho himself demonstrated in the 15-16 season. Progress isn't always linear. We've improved massively on Moyes and LVG, but that's an extraordinarily low bar to set. The fact we've sacked two successive managers isn't the problem...the issue is that those managers were both really, really bad at their jobs.
And I say this as someone who does acknowledge Mourinho's improved us, and who does think he should stay, but who also understands the frustrations of those who want him gone, and as someone who feels like his approach might just be a bit too outdated for us to stand a reasonable chance at winning the PL or CL while he's here. Pragmatic, defensive teams winning big competitions is the exception right as opposed to the norm, and while Mourinho's improved us I worry he'll struggle to take us much further unless he can't implement a more attacking approach.