Your backup center seems to be almost as good as him. Alternate your starting centers. One game a week with Dustin Ware (starter), Marvin Spain (backup), and Muratcan Savtunç (reserve). The next game have Marvin Spain (starter), Dustin Ware (backup), and Muratcan Savtunç (reserve). And for the scrimmage, have Savtunç play the whole 48 minutes.