Here's what I think is happening. There are still some good, honest people in the FBI and intelligence agencies who are aghast at what has happened during the Obama Admin. But they were isolated and vulnerable. It probably took a lot of time and effort to get them inoculated from counterattacks - and Sarah Carter and John Solomon were part of that process by reporting on carefully-targeted leaks. With that done, they could tell what they know behind the scenes. An airtight case had to be gathered - we're dealing with the media and Democrats who demand absolute proof of wrongdoing, and then will still deny it - and I think we are at the start of that being case being presented.
And they finally found a bus large enough to throw the Clintonistas under. And Mueller was quietly told that if he wants to preserve his reputation, he needs to be driving that bus.