While I agree somewhat with Zombywoof's assertion that it is the "parent's obsession," the fact is that more and more, if your son is not working to earn a position, someone else's son is. When tryouts come, that young man working on his game just might have an advantage. That is what parents stress over. In the end, when those tryouts happen, a pecking order is established that is difficult to overcome. Still, when players see that, those that really want to be on the field will give themselves a kick in the butt. The others will accept that they are second string. That is the nature of things.