Even with people calling Marcelo the best ever, I would argue that he is still underrated. he has innovated and contributed so much to the art/sport that we take for granted. The seatbelt grip that you learn in your first month of class? Marcelo got everyone doing that. Those arm drags from the butterfly or seated guard to the back that you learn so early? Yeah, he got those going as well.
Who else has taken such a common day 1 submission like the guillotine choke (children instinctively do it when they fight) and redefined the basics of it? The guy took an already successful submission and made it better on almost every level.
I can’t think of many people that introduced new techniques to the game, redefined existing techniques and made the refinements the new standard, and also had such competitive success. Not to mention his excellent skill as a coach, instructor, and and brought forth the current online training model. He was ahead of the curve on that as well.