Midfield - we need a major upgrade on McFred, and replace the ageing Matic. Our biggest problem this season, is midfield, who got outplayed by almost every opponents we've played. Keep VDB, replace the rest, including Pogba.
Defence - Sell Maguire, kick him out of the club, and buy another decent CB and full back. Our defence has been at Sunday league football level this season. We need to sort this out immediately.
Attack - We need to start playing with more pressing as unit, and more link up play among our attackers. Right now many of our attackers only played for themselves, and doesn't press as a unit at all. Whether Ronaldo will stay or not next season, we still need to buy another Cavani type of attacker, someone who would work their arse off for the team. A Rooney or Benzema type of forward would be ideal, not only for Ronaldo, but also for Greenwood or Rashford in future.