You are right, but I don't think it's impossible. In the post Ferguson era, Manchester United has struggled with inconsistencies, fitness issues, and the lack of the winning mentality that once made them a dominate force in the Premier League. This decline has seen them lose their status and become a mid table club.
I never expected the struggle to remain until this time because it has been long that Manchester United has been struggling even as they signed Moirinho. Although some coaches like Luis Van Gal, Jose Mourinho, David Moyes do tried their best for the team, but couldn’t meet the standard Ferguson set for the team, and I just hope Manchester United will get that standard because Manchester City had taken over Manchester in the past six seasons.
I personally think Manchester United would have picked up sooner if they had sacked Erik Ten Hag at the end of last season. ETH was a problem but Manchester United couldn’t see it until it was too late. Ruben Amorim had his first game in Manchester United yesterday, I think there is hope for Manchester United with Amorim as manager. It won't be an instant transformation but they will certainly be a big change in their performance.
I don’t know why the team management believed in him so much, maybe it was because of his past record and performance when coaching Ajax, but in Manchester United, the only achievement was the two trophies he won for the team, but after that, he destroyed the team and make them a struggling side now in the Premier League.
I hope Amorim will do better in Manchester United because he was doing well in his former club, I am sure if he have enough time to settle down, he can do better for Manchester United.