No student in a MS band drives. Which means requiring the band to be at any event requires parents of the community to adjust family plans to get their kid to the event and back home.
This makes it hard for you to require attendance at the event.
Does your band have any music ready to play at the game?
Do you have ball players and/or cheerleaders in band? What is the plan for them to participate in both events? What instrumentation do you have if they're not with you?