The pair won the World Cup together as part of Germany's triumphant 2014 squad.
"The way he creates goals... he's a player with a really good eye for his team-mates. He has so many assists in the Premier League and with the national team.
"He's just an intelligent player and you can see that right away with a first glance. I always enjoyed playing with him and that's why it's a pity he's taken a step back. I hope he'll get back to form and return to playing regularly for Arsenal."