The fact that Manchester United finished the season so poorly is also Amorim's fault, because he prioritized only the Europa League games, and he openly ignored the rest of the games. In the new season, I only hope that the team's attitude to the Premier League will be more responsible, but they do not have another more important tournament, so they will try as best they can. Pre-season games are not an indicator, because their opponents may not play at full strength, may make a lot of substitutions and so on.
Or maybe the level of teams in the Premier League is better than in the European League competition so that Manchester United could reach the final last season. Manchester United has prepared everything for next season including some new players so we can't be sure about their performance yet but on the other hand I am sure Man United will not finish in the top 4 because it is difficult to realize it.
The level of competition in the premier League is not better than the rest of European leagues competition what happen last season was that Manchester United was only desperate and needed to win the Europa League so that they can play in the champions League that was why they were so putting all efforts to make sure that they win the league, they where very poor in the Europa League group stages as they were drawing games