Season 2 of Westworld had fewer viewers than Ballers. Ballers. You're right; it's a huge-budget show, and one HBO clearly hopes will be a tentpole. But it's no Game of Thrones.
Would I rather own AMC than HBO? No (FX, though, different story). But AMC is a basic cable channel! Breaking Bad and Walking Dead are both much bigger deals than anything HBO has done in the last 10 years except for Game of Thrones. If we have to argue about which is the more important channel in 2018, HBO's model isn't working.