I don't think thats the case. I think that Pep wouldn't do any better with this set of players trying to play his style of football either. Same for Klopp/Slot. Amorims system needs runners. It needs players who will break through the opposition lines. We have almost none of those players. His system isn't crap, he just doesn't have any of the personnel required for it. This has been a problem for years at United. As soon as the opposition offer up any resistance we stop, check our runs and pass backwards and all momentum is gone. We aren't a possession based team who probe for gaps and have players with a high level of technique who can find gaps and play cute 1-2s.
A different manager would be getting far more from these players but ultimately the ceiling of this set of players is probably top 6-8.
The high ups at United certainly have a tricky decision to make now. £100m less to spend and a manager who needs more than a few players to come in. The safe option is to get rid of him and bring in a conventional 4 at the back manager and build on top of the current squad. The much more risky option is to back Amorim and hope that we aren't sacking him come Christmas and resetting again.