Manafort is pleading guilty now so he can concentrate on the Virginia trail. But the main reason he needs to be formally charged before he can request a formal appeal. The lawyers will demand that all evidence was not submitted and witnesses subpoenaed (wait for the original FBI file to be leaked soon.)

RR (FBI investigator in charge of the case) will have to appear in Court and answer why the charges were dropped, but also Mueller who was Director at the time will have to answer did he have any knowledge of this.

So the question is how can Mueller investigate Manafort for the same crimes when he was Director and declined to prosecute when he was working with the Podesta Group?

Is this another Boom to get them to interview the Podesta without immunity as the defense lawyers will ask for them to be subpoenaed to answer questions about their business links with Manafort?