If Man United has made a lot of improvements I believe their performance will improve but if they keep the existing players like last season I'm not sure Man United will perform well next season (IMO).
THIS! This will be the transfer that will make Manchester United a much better team, a team that could be in top four for a while, a position that they really need with the amount of money they are spending. This club once was among the highest income clubs of the world, and they screwed it up by being not so great, they need to get back there, and their defense is their biggest issue right now.
I understand that they bought Zirkee, but Hojlund wasn't that bad, whereas they lost Varane, and they still pray to god that Maguire plays decent whenever he gets the chance. They should have fired/sold Maguire already, and yet instead of doing that, they are still giving him some time, that is just not normal.
I believe that the best United can do right now would be buying defenders like that, Tah is a great defender and he will definitely help United concede much less goals, Onana probably won't be as bad as last season neither, so combine those will make a good return. This of course will cost a lot of money, and they already spend a lot, so spending a ton on yet another player will be a trouble for them, but this will be worth it, I mean I would sell Antony and put whatever I made from that into this transfer.