If your team rating sucks compared to the opponent and you have a guy with high RB he will get a a hefty share of rebounds, but you're still looking at much fewer overall possessions for your team. You're looking at something like this with a few more rebounds concentrated in some positions:
(85154449)No matter what your team rating is and your total rebounds compared to your opponent's, in a team with low RB at every position the boards will be split around. I have tons of examples about this.
I think the GE calculates ratings, determines the overall number of shots, ORs, steals, TOs etc etc and then assigns them to players based on skills and match ups. If your ratings are lower you will get fewer rebounds. If you have 18 RB players at PF and C your team ratings will be higher and you will get more rebounds and if the rest of the team sucks they will be heavily concentrated in those 2.
And as a mater of fact, playing the same exact lineup in inside tactics, gives higher RB ratings than any of the outside tactics.