Basketball at a public schools is typically supplemented through the booster club. If there is no booster club supporting the basketball program then nobody at the school really cares about basketball.
IF there is a booster club that cares about basketball, then stop the extra money flowing in and the situation will resolve itself in short order.
Varsity Coaches are hired to win games not excel in the classroom. If NOT winning games doesn’t get him fired, then your kid is at the wrong school if he’s serious about basketball.
