Introduce a small randomization into the positioning of the worlds in the list. For example, a 25% or 50% chance of adding or subtracting 100-500 points to that world’s rating (for positioning order purposes only, not real points). That way there’s a chance the green team in one group of 3 might end up being the red team in the bracket just above.
The problem this solves is the mapping problem: It’s nearly impossible to get the mapping title any more, because all of the worlds’ ratings are basically written in stone.