Honest question: somebody explain to me what a running/passing game coordinator does.
It is all gameplanning? Traditionally when you put a gameplan together you look at all your offensive plays and starting picking and choosing plays that have the greatest likelihood of success against the particular defense you're facing based on personnel, formation and alignment tendencies, etc.
So the run game coordinator says, "Let's put these run plays in the gameplan for this week's game against XYZ University."
Similarly, the passing game coordinator says, "Let's put these pass plays in."
At that point it would be standard stuff: the team practices the plays in the gameplan and the playcaller calls plays from the gameplan on gameday.