I'm not so sure it's so simple.
10 years ago when Ambramovic came in, Chelsea spent relatively, an awful lot of money. They bought 5 or so top bracket players each summer and sometimes more in the winter. Same when Man City started to do the same. Some came in and did well, some didn't and were moved on. The problem now is that these players are no longer £15m and want £100,000pw. They want £200k+ and cost £40-£60m, with that only set to increase.
Considering how many of these players Man U need in order to go down the route of just buying or "re-organising" the squad, I just don't see how that's feasible from a business or even a FFP POV.
What should be being done is Man U buying 10-15 moderate, potentially good players, shifting 80-90% of the squad on and building what's left into a team, then adding star players to it. That could work. It would also take 2-3 years, if successful, to begin to bear fruit. That's what clubs without managers that have been there for 20 odd years do. If they don't work, they get the sack and the next fella does the same. That's what you do when you've not got unlimited money.
At the moment, the transfer strategy seems completely opportunistic with no clear vision of team progression. The 3 at the back thing is a complete red herring. It'll all just become a circular pattern of thinking the addition of 1 or 2 great players each season will fix the team and therefore the club, when it wont. It's exactly what Liverpool did towards the end of the 80s, it rots the club and the team from the inside.
On the plus side (from your owners POV) it keeps attendances high, TV exposure high and there are plenty of cup competitions to win and gloss over the mismanagement.
Anyway. It doesn't really matter what I think