His transfer record at City is incredible. Many on here believe in the myth that he just keeps binning expensive players to buy others but when you look at his top 15 transfers while at City (not sure about the fees, took them from transfermarkt but they might be off sometimes):
1. Grealish £100m - still at the club and having an important role this year
2. Dias £60m - still there and important
3. Rodri £60m - plays every game
4. Mahrez £60m - important squad player
5. Laporte £55m - important squad player
6. Cancelo £50m - used to be vital, will probably be sold for profit
7. Haaland £50m - incredible
8. Mendy £48m - in jail
9. Stones £47m - recycled into a class defender / defensive midfielder
10. Walker £45m - gave then years if quality service
11. Sane £45m - sold for profit
12. Bernardo £40m - incredible
13. Phillips £38m - shite
14. Ake £37m - turned into a quality defender
15. Ederson £35m - awesome
So basically out of 15 players he bought, maybe 2-3 were really overpriced, 11 are still there and have a role, 1 has been sold for significant profit after some good years, 1 is on loan after some decent years, 1 has no real use and 1 is in jail. And when you go down the list, it still has some quality cheap signings like Akanji, Alvarez, and hardly any that were complete waste of money.
Compare this to our list in the same period:
1. Pogba £90m - released for nothing at the end of his contract
2. Antony £80m - probably going to be a decent squad player
3. Maguire £80m - awful
4. Sancho £75m - awful
5. Casemiro £70m - probably good, though short term signing
6. Bruno £58m - awesome
7. Martinez £55m - awesome
8. Wan-Bissaka £50m - overpriced like hell
9. Fred £50m - overpriced as hell
10. VDB £38m - waste of money
11. Mkhitaryan £36m - waste of money
12. Varane £35m - great when healthy
13. Lindelof £34m - mostly bench fodder
14. Matic £34m - had maybe two good seasons
15. Bailly £30m - waste of money
If anything, out of those two clubs during this era we have been utilizing 'replace expensive player with another expensive player' approach far more.