Should I drop Marques Colston and pick up Brandon Marshall?

Colston is a better fantasy WR than Marshall right now. The dolphins have a bad offense with no running game to keep defenses honest. NO is back to a more high powered offense. You think it's a good idea to drop a player who actually is putting up good numbers on a playoff contender for a player who might put up good numbers if a lot of things turn around for Miami miraculously over the rest of the season? I would certainly not make this move.