The Germany international has been linked with a return home.
"If you look at the number of games he has played, with the number of goals he has scored and the number of assists he has, he is a very efficient player," Wenger said. "He can play as a second striker hanging behind but he's not a guy who likes contact up front.
"He likes to run in behind and get the ball to feet basically. When he gets in the box, and has a chance to score, he is the one you want to have the ball. He is very accurate, very quick, has a short backlift and is a quick, fantastic finisher. That's why everyone says he is a striker.
"But when he plays up front, completely up front, you don't feel he enjoys it. He likes to come to the ball and always come deep.
"He is happy to play where he plays. He has over 100 caps with Germany and does not have one cap with Germany in the middle. Over 100 caps on the left. You cannot say it is not his job - he is happy there. He made a great international career there."