At the moment I'd probably peg him at a similar mould to Herrera. Not quite creative or cultured enough to arrest creative responsibility for a team at #10, but I wouldn't play him in a midfield two as an #8. I think he'd play best in a three man midfield with a defensively competent (offensively sound) #8 (Vidal) next to him and a proper playmaking #6 (Pirlo) behind.
In future if he can sort out his game intelligence, mentality and improve his balance, he might be able to play either 8 or 10 to a high level.