Why is evan turner played randomley?

last night he got no minutes, tonight against boston he played for almost 32 minutes and went 9-14 on field goals. He needs to be playing at least 30 minutes EVERY night for the for him to develop into the star he is capable of? to me im really questioning why their coach is really not playing him much? I mean really, Evan Turner is the future of their organization right, Iggy is already almost 30 years and is not a true leader. Why do you guys think the coach doesnt play Evan Turner alot?