If you look at Manchester United's ability under Ruben Amorim's coaching, there are still some weaknesses and I witnessed when they lost at home against Nottingham Forest, where Manchester United were unable to do much and instead they had difficulty keeping up with the attacks built by Nottingham Forest players. If we look at the results, I am pessimistic that Amorim can present a trophy in their first season because even though in the Europa League the teams they faced were not too strong, there are always surprises in the competition and we would never have guessed how Atalanta could beat Leverkusen who at that time performed quite impressively.
It seems that Amorim must change the formation that he has used for Manchester United players in the upcoming matches, because I see Mainoo really does not live in a formation like that even though he is one of the very good players at Manchester United at the moment apart from several players in the front line. Because Amorim who is new to Manchester United must try more new things in the team so he can know what is more suitable for the team at this time because I also thought that Manchester United could win at home when hosting Nottingham Forest. But in fact they lost at home.
I don't think the style of formation Amorim uses is the problem. His 3-4-3 formation works for him. We saw him use the same formation at Sporting CP and he flourished with it, even in the Champions League too where he used such similar formation to win Manchester City. I think it's the players that needs to adjust to the coach tactical strategy and formation. Manchester players are so weak and lazy, most players don't have the stamina to play in such a rigorous formation. For Amorim to effectively implement this formation, he would have to offload the current team and buy new players.