I pointed out earlier that according to transfermarkt (which you can and should take with a grain of salt), City's tranfers were more overpriced than the other PL teams. The gap between what City paid for players and their "market value at debut" was like 300m.
Taken seriously, that would mean that either:
- Guardiola has improved players that weren't that good, but overpaid to get them.
- City has a method to detect the 'true value' of players, and they then pay their actual value for them, which looks 'overpriced' to the rest of the world. With these players of truly high value, they build PL-dominating teams.
Both of those are equally impressive.