But that is natural because it is not easy to lift the performance of a team from the bottom instantly, it will definitely take a process. However, I also agree that some Manchester United players are not at their best level, there are players who have not been able to show their best game and some are slowly showing better. This is a challenge for Amorim to solve the problem.
Aside that, people are quick to forget that it's not easy to take up a team mid season and introduce an entirely new tactical system different from what they're used to. There's no preseason and time to blend the players. Amorim is doing is best and I think he'll keep testing his players in the rest of the EPL matches while his main focus will be on the europa league because that's their only shot at champions league football. About underperforming players, I believe he's assessing the team and taking notes. At the end of the season, players that do not fit into his style will be released to make room for new ones.
Amorim is not a magician, and for a team to pick form is a gradual process. You don't expect Amorim to come to United and start winning matches back to back as if he is the king of EPL. Don't forget that EPL is not an easy league because mediocre clubs can become strong when playing against a big team. Let Amorim get the players of his choice and let's see what he gat.