User blog comment:B214/Question and Answers 3/@comment-24098614-20140716003255/@comment-1359322-20140716063743

It's not that the Bael was next in line, but as the highest ranking Devil among the 72 Pillars, the Bael instantly became the leader replacing the Maous, but since the Devils needs the Maous as figurehead, so they have to find 4 Devils to act as Maou.