Yes, it means that the player (your son) has little chance of breaking into the top 5 player list right now. Or you haven't been to a practice in a while. Looking at that list of attackman there are two kids that will not be replaced as starters as long as they keep showing up. So in reality there are 4 spots that could be filled and the bar is pretty high. Or move your son to M.

IMO I would make my son the "7th" out 6 attackman on that team if he were playing up like the coaches son. For now, I would hold a spot for a good player as the 6th spot and its placeholder is the coaches son.