Just to expand a little on my own thoughts, if you want to succeed, you have to try. Success doesn't fall in your lap by happenstance. It may be "just a game", but it's also a teaching tool for young men. Organized sports in general allow for a way to teach children that hard work and dedication leads to its own rewards. If you're facing kids unwilling to work hard, unwilling to dedicate themselves to getting better, it leads to frustration. Coaches are a different kind of educator. Teachers educate the mind intellectually, coaches educate the mind morally(though that doesn't feel like quite the word I'm looking for). Just like a teacher gets frustrated when a student fails to put forth effort, so does a coach. They're each trying to help a kid better themselves, but the kid is unwilling to learn. It's about discipline, self respect, and effort.