Mevlin Anthony manages it and he's no better than RR
Melvin Anthony is a lot more well known that RR and RR is not even close to Melvin in terms of shape and structure. RR was in superb conditioning. Not saying it's fair, it is what it is. BB right now is about packing the most mass one possibly can on a physique.
For a shorter guy to make an impact against the freaks, He'd have to have unGodly type mass, and that doesn't really work either. Look at Lee P, great mass for his size, but put him next to Cutler, Coleman, or Rhul and he disappears.
There are of course Polar opposites, Small guys that are shredded and Big tall guys that make you say OMG. They are simply in the show to stir controversy and have people going He should have won. Maybe next year......securing tickets for the next big show.
IFBB shows are simply to display what is humanly possible, if you want to see a contest, go to the bigger NPC events. Weight classes make it so BB contests are judged somewhat fairly.