Of course he was a plant.  Trump didn't have a team of experienced political persons around him. He came recommended. By Roger Stone. Manafort was well known in the swamp. I believe Trump initially thought he was straight up, but then realized he wasn't. Trump will not pardon him. Remember that the entire landscape is corrupted. Trump had to wade through the sh%t and he has been doing that ever since....Decent story about Manafort here:    Manafort story