The difficulty level of the Premier League is much higher than the Portuguese League. That's why Amorim, like Ten Hag who was brought from Ajax, may not give a good image. Manchester United is taking a big risk. They are bringing a coach from a small league to the team again. I thought they realized this mistake and would not make it again, I can say that I am very surprised.
I read in some media that Ruben Amorim managed to make Sporting dominate the league again after several previous seasons always being in the middle of the table. Of course the competition in the English league is different from the Portuguese league. The EPL has a high level of difficulty and of course this is a risky bet. However, I think one of the reasons Ruben Amorim was chosen is because he can play and maximize the available resources. This is important for United who have spent a lot of players in the transfer market this season. I don't think Ruben Amorim can improve the performance. But I expect them to perform better than when coached by Ten Hag.
If you look at Ten Hag's achievements at Ajax, he is better than Ruben Amorim at Sporting, but in fact after arriving at Old Trafford Ten Hag still has not been able to bring Man United to compete again in the EPL. Moreover, as you said, the competition in the English league with the Portuguese league is very different, this is extraordinary courage for Ruben Amorim who dares to take high risks. Hopefully he will not suffer the same fate as Ten Hag.
So far, Ruben Amorim, who is a coach who has a defensive tactical strategy and wing attacks, has finally box to box from every Sporting match. If you look at the system, it is very good to be applied at Man United. He only needs to adjust to the existing player material, and hopefully he can also fix the dressing room and the players are no longer selfish when playing. At Sporting he used a standard 3-4-3 formation, we hope he can quickly adapt to Man United and be able to restore Man United's glory.