Looking at Manchester United's impressive performance so far, it is very possible for them to finish in the top 4, but if we go back to the start of the season, that is not Manchester United's target, they should be able to become champions or compete fiercely for the title with the strength they have , but unfortunately at the start of the season the team coached by Ten Hag was unable to be consistent and also unable to display their best performance.
Manchester United don't have impressive performances in this season but you are right if you only say it for their recent performances. They are playing better and narrowing down differences with Tottenham Hotspur and Aston Villa but they have yet taken over the fourth position. Gaps are still far enough but if they can maintain good performances, they will see top four more nearly and more achievable.
Because this season has gone through two thirds of its length and there is no much time and matches for Manchester United to make mistakes and correct their mistakes. Past mistakes already cost them gaps with Tottenham Hotspur and Aston Villa so now it's their very last matches to correct their past mistakes, not to make more new ones.