It would be massive for us if Willian keeps improving and can recover the level he was at at Chelsea. He's the player that suits the role ESR has been recently, a "wide playmaker" coming off the left, the best in the squad. I think we look the best when we have a player like that on the left.
One thing I noticed about Willian, even when he was playing poorly is that his physical level hasn't dropped off. He was hustling around like a much younger player, but nothing was coming off for him. Hopefully he can maintain this level for the next couple of years. He's got that rangy toughness of a vardy/ibrahamovic which should see him be active till quite late in his career.