I struggle to see how some fans think a new manager can do anything different with our players. For 5 seasons and more we've all been saying we have players in our squad who aren't good enough for Utd, players signed under previous managers. Some of those players are still here (Jones, Smalling, Rojo, Young, Fellaini, Valencia, Darmian).
We have players who have played inconsistently for several seasons despite changes in manager (Mata, Lingard, Herrera). And we have players not playing to their potential now (Pogba, Lukaku, Rashford, Martial).
So of a first team squad of 26, we have 7 players we all think shouldn't get anywhere near a Utd shirt to begin with (and personally I could add others to the list - McTominay for example), 3 players who have only ever played inconsistently for Utd, and 4 players out of form. So more than half the available squad aren't performing or were never capable of performing to Utd standards. That won't change because a new manager comes in because we're on our third manager to date and still suffering.
We need a clear out of players, which Jose started, but we need it much faster, and we need to invest in better quality players. And investment does mean proven quality players. Look at our RB situation, we have a past it Valencia backed up by an inexperienced Dalot. That is a daft position to be in.