The real problem with summer travel ball is the pitchers. You can only pitch so many innings. So where do you pitch your innings? If you need to show your high school coach that your a pitcher to be considered for next spring, you'd better be pitching some quality innings for your high school team. If you already have established yourself as a pitcher the previous spring, the travel teams see much tougher line ups than what you'll see in summer high school ball (until the tourney). The problem is it is easy to let your kid pitch too many innings on the weekend and ruin his arm.
Just to note my son faced some very tough high school varsity teams this spring and did very well as a sophmore pitcher. But the team that hit him the hardest all year was a sixteen year old travel ball team this summer. They did better against him than the number two varsity team in the state did last May. Go figure.