Whether or not he is a center is the wrong question.
The question to ask is, why is our best outside shooter, percentage wise, who happens to be 7 feet tall, not taking more shots? I feel like it is a combination of (I) he lacks assertiveness, (II) his team-mates, most of whom are inferior shooters, taking shots that they should not be taking, and (III) foul-trouble, which is killing his minutes.
Stevens needs to get a little angry with him, and tell him he is hurting the team (therefore, being selfish) by not asserting himself on offense better.
He could be a 20 ppg scorer easily. Just don't know if he has got the heart.