Those amenities could be shared with the ball parks and soccer field. Having everything clustered on campus opens a lot of opportunities to make the events a destination, where they would be in place for track, softball, soccer, and baseball. Decent rest rooms. What about a place for food trucks? Maybe place things to do near the entrance of the Team Shop. Draw more people into there.
Most minor league baseball fans don't care whether the team is AA, A, independent league. Or what those mean. They go for an affordable day outside at a decent facility with a choice of foods. And maybe one day being able to say "I saw them play back when...". Schedule several games/events at once to make it worthwhile. Charge admission to ball games. IMO that would help attendance.
Make it more "something to do" than going to watch a game or event.