Increase consistency, increase goal productivity, improve defense and get other creative players who can help build attacks. That's what Manchester United has to do if they want to be in the top four of the standings this season, otherwise, Manchester United can't hope for anything at all.
I'm not sure Ten Hag can do that throughout this season, the team's inconsistency in performance is the reason. They played well in some games, while playing so badly in others. Ten Hag sometimes finds solutions to make his plans go smoothly, but sometimes he is completely silent as if he doesn't know what to do. Thus, I don't believe in Manchester United yet and so far only Manchester City can maintain that consistency, not even Liverpool or Arsenal.
Given the points you mentioned, I don't think Ten Hag would be able to do that. Ten Hag also coached Manchester United for the last two seasons. We have never seen better performances from Manchester United. Manchester United's performances in the last two seasons have been very erratic and poor. And this season we are seeing a repeat of the same thing. Manchester United's performance this season is also very erratic.
Manchester United's big win against Southampton is nothing to be happy about. Manchester United will face Crystal Palace and Tottenham in the next two matches. And I have full faith that Manchester United team will not be able to get 6 points in these two matches.