Pop words of the wiser

This book is about a kid named Marcus and he is a Quarter Back for his undefeated team but he is not the starter QB. He wants to become a starter but he doesn't want to hurt the team. He practices every day at his local park. When he plays their he meets a retired NFL player named Charlie. but since the player has Alzheimer's he doesn't remember his 14 year NFL career. And Marcus doesn't know because he was an old player. One day when they are practicing together Charlie said " remember the coach knows what he is doing don't get mad at the coach he can take you out like that" then he snaps his fingers." Marcus remembers that and doesn't get mad at coach for not putting him in as much because the coach is the smartest man in the team.