You have been drilling it into his head that he has to step up his game if he wants to make the traveling team. The first places children look for clues about how to behave are to adult role models. As a parent, it's especially important for you to model appropriate behavior. Of course, even if you are a great role model of good sportsmanship, your young athletes still need help in learning how to behave that way. Anger and frustration are a part of sports.
Children can get upset when they lose, make an error, or miss an easy volley.
Getting shown up in front of teammates or family members can also trigger their anger. One of the beauties of sports is that they present ideal opportunities for teaching children life lessons. You can use sports to help kids learn to cope with frustrating and angry feelings. Learning to deal with those feelings will help them handle frustrations off the field, as well.