The reality is that after a few true "studs" most players have equivalent talent. In order to seperate this talent, coaches look to various things -- attitude, hustle, personal bias, politics and the very common "hot mom."
Frankly, it would be easier if they would just admit that other factors besides raw talent play a role. Issues occur when they try to give the "smoke screen" that talent is what they base their decisions on. I have been thru the "all star" thing a few times and while they tried to give the appearance of impartiality, it was clear that politics played a role. Right or wrong, that is called life.