He finished 1st in the AFC and 4th in the entire NFL in rushing yards last year, despite missing 2 games. He did that behind, and I think unanimously we agree, one of the worst offensive lines in the nfl last year. Mixon is a talented back, and in fantasy, if every good back that played for a crappy oline team was considered "dead weight", then Le'Veon Bell would be a free agent. Mixon is still a solid RB2. The reason the points are low is obvious - the team can't get him close to the end zone. He is still averaging decent numbers regardless, and the Cincy offense is clearly shifting the focus from Green to Mixon.
Your argument on "Mixon is dead weight" is 20/20 hindsight. It's easy to look at what a player has done so far and just regurgitate numbers. People were saying that John Ross and Demarcus Robinson were studs thru the first two weeks. Now look. I don't own Mixon in any league, but I certainly wouldn't mind owning him. He is a proven solid back, and I have no doubt that he can produce...he's done it before and there really is no evidence to suggest that he is incapable of doing it again.