I'm not sure we saw the best of him. I think he's more of a 10 than a wide player but neither Martinez nor Koeman gave him any time there, despite him having played that role for Spain's young sides. One thing I definitely don't see him as is the hard working, up and down the line type. So it's clear he's not gonna fit with Koeman's plans.
I suspect he'll do well enough back in Spain, altho I don't see him breaking into the Barca team anytime soon. Not sure the Premier League will ever really be a 'good' league for his talents tho.