Should I quit my son's high school soccer booster club?

The high school soccer team has become too intense for me. The Coach does not know enough about soccer and has cost us some games. Our record last year was a pityful 5-15-3 which he takes no accountability for. He plays favorites with players and their parents plus I have never been one to kiss up. I want my kid to earn his play time (which he has) but we find that these "favorite players" only pass to each other. My son also plays for a highly competetive club team which he loves. I'm afraid quiting will send a bad signal and hurt my son's remaining high school career.