Hype. Granted, it is remarkable how reputable, switched-on managers like Pochettino still fall for it, but when £30m represents slightly more than pocket change for English CL clubs, signings like this will continue to happen.
Its still 16% of Tottenham's total revenue last year. Remove all the normal expenses (wages ect) and its pretty much everything they had. No doubt in the coming year revenue will increase again, they can certainly afford it, but its still going to be a significant chunk of their cash flow.
Aye but not to worry, if they only have him for this season they only owe us £6M.