We got away from doing auditions a few years ago and just do band placements for our four bands. While the student's grades "dont matter" for CSR, they matter for most other events, but more importantly my argument for not moving them into higher ensembles is simply this: They are clearly having issues with their grades. Maybe they need to be in an ensemble that is a little bit less challenging or demanding of their time. I try to have conversations with the student to see what the issue is and I may even have conversations with the teachers to get their input of the students performance in their class. From my perspective it is not a punishment, but genuinely trying to help them get on the right right.