Amorim has only been Manchester United manager for half a year after replacing Erik Ten Hak.
It's not easy to make big changes to a team that's experiencing a decline in performance because they need real change, and I'm sure Amorim can gradually do that.
It is hard for players who come in winter transfer market to have good adaptation and significant contribution for their new clubs and it's similar with head coaches who are appointed in winter transfer season too. Ruben Amorim came to Manchester United last season in middle of season and he surely had difficulty to make good contributions with limited resources he had.
It will be different in a next season as he already had a half of season to test his players, tactics, and recent months with the summer transfer market to sell and buy players for getting player resource he wants for his team. The coming season will be very challenging for Ruben Amorim to show off his management capability and he will have nothing to blame on if his management and results are bad.