some kids worse than my son got to make team before.

because they have enough players and they don't need replace players very good. How much is the skill differeance in three games? Why two is replace and next one is starter? winning is every thing here. If your son is very good and he can get one or two goals when he was on game, you bet he would be starter next game and keep this position. all we did is blame our kids skills is not as good as other best players in team. but you have to look the same level kids to compare. I had spoken to coach before even video tape the game as evidance. In the work place is the same thing. you have to be the only one can do it then you get a raise.
Of couse you don't need let young kids to know this when they are less 13Y. I point that out when my No 1 is 13Y and asked him his choise. He now know for every thing he do he need to be the best to compete with his white peers. life is never fair and he learned this in his young age.