The most worrying aspect of José's tenure here has been his inability to evolve tactically. Ten-to-fifteen years ago, José was undoubtedly the foremost tactical pioneer of his time. Now however, I feel that he has failed to embrace how the game is changing. If you go back to the early 2000s, I would go so far as to say that both attacking and defensive play was much more unstructured than it is today in that managers didn't obsessively focus on positioning and passing in the way that people like José and Guardiola do now (Defensive positioning for José and passing for Guardiola). José took advantage of that from the mid-2000s onward by organising his defence far more effectively than his managerial counterparts. However, adaptation is crucial to survival; other managers around him adapted their defensive systems too, and soon José's defensive advantage had been eroded.
From 2008 onward, Guardiola is the predominant tactical pioneer; in order to keep up with him, managers must adapt how they approach attacking play. However, José still seems to be resisting the call to change, instead believing that worked a decade ago will still work now. Personally, I feel that a laissez-faire approach to organising attacking play is out-dated; consequently, I feel that United won't really make much progress for as long as José is here.
Also, you have to question yourself is José maximising the talents of the players at the club. If Pogba, Sanchez et al continue to under-perform; there are two possible explanations; either these potentially elite-level players are all coincidentally under-performing, or José is failing to get the best out of them. Considering that the first explanation is unlikely given that top-level players shouldn't all coincidentally under-perform for a sustained period of time, I would say that the second explanation is the more likely answer.
Moreover, it only makes sense to sack a manager if you have a viable replacement. If you were to look at Sarri, Tuchel, and Pochettino for instance, they have all embraced the changing game more readily than José; in addition, these managers have generally made efficient use of comparably limited resources at their clubs. IMO, these three managers would have us both performing better and getting better results this season than José had they been United manager.
