Unfortunately, it seems that Manchester United changes coaches but they all think the same way and make the same mistakes. For example, there is Victor Osimhen who is a very skilled striker, but Manchester United stops signing him and spends a lot of money signing players without great skills. So it is difficult for a team to have good results when they have this bad behavior.
Let's look at the squad of Liverpool, Arsenal, Manchester City, they have players with great skills from the attack, midfielders and defenders. But Manchester United doesn't have that.
Looking back from time after Alex Ferguson I feel the board of directors also have a hand in these bad signing of players. I have also heard Manchester United supporters on several occasions including coaches complain that they don’t have 100 percent choice in player selections and most times the club make these signings on their terms and offer to the coach to do his best with them. I think the coaches should be given the right to make their choices and finances made available to get these choices.