I, too, was once a bench-warmer. Still, mama is wrong. It may be painful to face, but not every child can play competitive sports. If they could, every boy over the age of 10 would become an NFL star. Generally, younger children play non-competitive sports where scores aren't recorded and all children are allowed to play no matter what their ability.
Older children enter the world of competitive sports where ability does matter.
You earn your position on a team and the better, older boys generally dominate the playing time, especially in football. The problem is, parents often confuse the two. When a child reaches 10 or 11, he usually begins playing competitive sports. While the child might accept that, often his parents do not. As in the case of the recent letter writer, some parents believe all children should play regardless of ability.