The "big league" thing has to be a reference to PSG.De Koster also said De Bruyne was PSG's main option but more expensive than Di Maria so they opted for the Argentine instead.
De Koster (De Bruyne's agent): "... the guarantee to play for domestic titles and in Europe and then the financial aspect."
De Koster (De Bruyne's agent) to Sport/Voetbalmagazine: "At a club like City, you get a great complete package: a big league, big respect..