The former Real Madrid midfielder has struggled for form since the New Year.
"When he first came into the team he was outstanding and gave a lift to the rest of the players," Graham said.
"But his form has dipped very much and I think the pace and intensity of the English game have caught up with him. He looks sad now and mentally he needs to come back."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball