"Yes, clearly he has the potential," the Spaniard told liverpoolfc.tv. "He has pace and ability, and also a very good mentality. He's a good professional.
"We knew when we signed him that he was a player with potential, it was just about giving him the confidence.
"When you play as a left-winger in another system - because he was playing 4-3-3 in Holland - and then come here and have to play 4-4-2 or 4-2-3-1, it's different for him; there are different things you have to do. He was learning when he came here."