Wenger feels the Wales midfielder is beginning to reach his potential.
"He has a fantastic engine and fantastic qualities," said the Arsenal manager. "He has to use that in a very intelligent way. I believe he is an intelligent player who understands football well.
"If he can bring his qualities to the team play, he will be an absolutely outstanding player, which I think he will be. He takes things on board and tries to do what you ask him to do and in the last two games you could see a really positive transformation in his game."