Every system has its pros and cons and, even if this United team were used to playing 3-4-3, there are still issues that come with using that shape.
While having Garnacho and Fernandes playing inside worked in an attacking sense, it meant Ipswich's full-backs could get up the pitch very easily, and double up with their wingers to give them overloads in the wide areas.
The other problem with that formation is that it asks the two central midfielders to cover a lot of ground, particularly in a league as demanding as the Premier League.
Casemiro and Christian Eriksen had a lot of work to do, and you could argue that the athleticism that is required is not their strongest trait. Ipswich played well and made it difficult for them, by dragging them everywhere.
To play that role well, United's midfielders will need to be more than just mobile, too. They will both have to love the defensive side of the game and be able to spot danger then be fast enough to stop it.
In the long run, I think Manuel Ugarte will be one of them. He needs a run of games to get his sharpness back but we have seen glimpses of how good he is, for example in the Europa League against Fenerbahce last month, and he has flourished under Amorim at Sporting before.
As for who Ugarte will have alongside him, well it will probably be someone who is not at the club at the moment - there is going to have to be activity in the next couple of transfer window for them to get the type of player Amorim requires.
Until that happens, United are always going to find it hard without the ball but this team is going to evolve, and so could Amorim's tactics.
As I said on MOTD2, I would be amazed if United are still playing the same 3-4-3 system in a year's time because the Premier League is very different to continental leagues.
If United are going to improve and become competitive for the title, I think Amorim's formation will evolve into something else but, in the meantime, at least their fans have already seen some progress.
Danny Murphy was speaking to BBC Sport's Chris Bevan.