The Mueller investigation has always been theatrical. Carefully placed leaks were used to create suspense. Every move was telegraphed beforehand.
There are two reasons why this sort of thing gets done.
1. It maintains public interest in the investigation.
2. It intimidates potential targets.
The Manafort indictment was as predictable as rain in Seattle. All the leaks create drama. But there's still nothing there. The indictment of Manafort and Co. has nothing to do with Trump. There are more unregistered foreign agents running around Washington D.C. than stray cats. The Feds can indict a ham sandwich. But all the grandstanding is there to boost Mueller's profile and intimidate other targets.
Paying attention to it gives Mueller what he wants.
Preet Bharara, the controversial former U.S. Attorney fired by Trump, mastered the art when he was terrorizing New York's political establishment. And it initially appeared to pay off. Preet Bharara landed some of the biggest Dem and GOP figures in the state. But since then the whole thing has fallen apart.
There's a lesson here for the media types waiting on Mueller. It's easier to conduct legal theater than to deliver.