[dmurray]

Have private security work the private event. Send a token number of police along, at the city's expense (the same number they'd normally assign to an area with 50,000 people out and about, so the sports event isn't sucking disproportionate resources).

If the stadium is such a hotbed of crime and disorder that private security can't handle it and they really need to escalate constantly to involve armed law enforcement, stop allowing it to host games at all.