That's right
Manchester united need to find a solution to their defence instead of bringing more midelfilders because they already have many good players there... Ronaldo is leaving the worst days in his career as a player and i don't really know how the player will manage to exit from this situation
Currently it is very difficult to get good defenders to be signed by the Manchester United team, because on average the best defenders have already been taken by other teams in the transfer market and Manchester United still need to fight harder to get good defenders now. And another option besides that is to train old defenders to be even better this season.