Leeds is an interesting comparison, they were in the PL a couple of seasons ago and we're a parachute payments club when they were promoted last season. Their players from last season still in their first 11.
Of those featuring the most, only Tanaka has little or no top flight experience prior to this season in in of the big 5 European leagues (PL, Bundesliga, Series A, Ligue 1, La Liga)
Ampadu - 89 apps in PL, Bundesliga and Serie A before jointing Leeds
Rodon - 29 PL and Ligue 1 apps signed for £11m
Struijk - 75 PL apps
Bogle - 50 PL apps
Aaronson - 68 apps in PL and Bundesliga signed for £24m
Dan James - 103 apps in PL, joined for £25m
Tanaka - no top top flight experience
Darlow - 7 seasons as second choice in PL and 40+ PL games
It shows they used their parachute payments money well, building for the PL, not just for promotion.
And we know the Sunderland splashed nearly £200m last summer with a net spend of £150m