He seems to be a heck of a trainer. As a former fighter himself, he understands how fighters think, much like Roach, and seems to make great connections with guys in the gym. He has a great job with Provodnikov, in a sense that he seems to give him confidence. He can't change his style at this point, but he can bring out the best his style has to offer, and I think that he has. When Freddie does retire, Marvin could emerge as a big name in the sport.
Don't know much about him, but that roach totally trusted him with rustan and is his protege... The guy must be promising. Freddie has a big mouth and gets away with a lot, but he's a genius at his craft, and knows potential.