Hope we don't pay too much for the guy (with Marotta you never know).
This deal reminds me of Lazio's deal with Zarate (young argentian talent with lots of potential), and they've paid close to 20 mil (even less then our reported price with Iturbe) for a

potential

and that turned out to be a stupid move (same could be said about Pato and Milan).
That differentiate a good negotiater from a bad one, you don't pay extra $$ for a player because potentially one day in the future he "might" be great. You pay what he's worth today.
Been working in real estate market for years and I see deals like that happens everyday from some ignorant buyers (pays a lot for a building because he thinks the rents will go up infinitely and life will be wonderful forever) and when the markets turns around they get screwed and wonder what happened.
On the hand, great buyers tend to pay what a land or building worth today and not a cent more than that. In most cases, they turned out to be right.