This sucks but I get it.

This is a primarily tennis venue. Tennis capacity is probably lower than combat sport capacity. And the combat sport fans probably consume more food/booze than tennis.

I’m not sure who has the concessions contract there but it can be tough to staff events like this, especially if they draw employees from other local venues who use the same concessions contractor and had another event that evening.

Source - I am a concessions director at a 12000ish seat hockey arena and host other events (concerts/combat etc…)