We had the same with Liam Bridcutt trying to force a move to join Poyet at Sunderland. Oh I forgot to mention the pace of Knockaert, it's also a clear advantage if we are comparing the two.
He might be 'everywhere' when he's on the ball. But will he run 70yards back to get the ball back, put his in a tackle, close down or track a man? Because that's what Knockaert does.