Is he a straight replacement for Hernán Perez? Yes and no. He can play on the wing, but he's more of a creative player like a Trigueros than a strict winger. Which means, like Trigueros, he can play in the doble pivote, or be out wide.
He is currently out of action with a dislocated shoulder, but should return soon (sounds like he should be ready for the matches after Valentine's Day with any luck).
He's only 19, and looks it--but he does have a reputation as a creative player. initial reaction on twitter has been quite positive. I don't see him as adding a lot right away, but he sounds like the kind of player we might enjoy. Though we have been getting away from the dominating possession mode, which he flourishes in.
BTW, his release clause is €22m--shows you how much upside he has (transfermarkt already puts his value at €8m)
We'll update with any more transfer news as we have it. Endavant Villarreal!