Two things. First, that's a normal FBI, not one run by a guy who was sentenced to 14 years in prison before Trump gave him clemency, and Trump's FBI and judicial resources have been utilized in some pretty unusual ways.
Second, the conviction rate is high, sometimes for reasons that have nothing to do with commission of a crime. They could get a "conviction" for something miniscule that wouldn't even send a subject to jail just because they have deep pockets and the accused would rather take the slap on the wrist rather than be sitting for potentially years without income while their savings are going to a defense firm. Technically, they still get a conviction, even if a plea offer is accepted.
And I don't know if Chauncey did something wrong or not. Just saying sometimes numbers and circumstances don't tell the whole story.