The NFL has a problem. It has friends in low places. Some of those friends showed up Saturday night at Candlestick Park. They turned the parking lot and some parts of the stadium into a fight club and combat zone.

This was very bad. But don’t buy the notion that this was isolated to a Raiders-49ers matchup. You can end the annual preseason game between the two teams-which will happen at least temporarily, according to a Monday announcement-and it still does not solve the problem.

How do I know? Because I have seen too much, in too many other places. Maybe not shootings in parking lots (what kinds of people bring guns to football games, anyway?), but other bad stuff.

I have been to New England where a grown man, obviously inebriated, decided to urinate on my rental car tires, just minutes after I pulled into the parking lot. At a Philadelphia Eagles home game, I have seen bottle rockets and cherry bombs fly through the air above the stadium as fights broke out in the seats. In 2004, a man was beaten unconscious in the stands at a San Diego Chargers home game.

This is why it is wrong to focus solely on Saturday’s idiocy. Authorities have reacted to it. Measures have been implemented. I would wager that there will be far less mayhem at this weekend’s home 49ers and Raiders exhibition games. But there will still be issues.

The most frequent complaint I hear from average fans who attend NFL games, here and elsewhere, is that they end up sitting in a section where loudmouth, drunk guys are insulting other fans — usually from the opposing team — and often trying to provoke a fight.

“I won’t take my kids to a game,” these people tell me so often that I hear the words even before they are spoken.

Is the NFL proud of that? It is probably true that Saturday night’s troublemakers were not season ticket holders and instead bought seats cheap on the secondary market. It is surely true that they were bringing ugly baggage from outside the stadium that led to the violence, whatever that ugly baggage was. But think about this: Why did they choose to bring it to an NFL game instead of somewhere else?

The bottom line is, if you plan to stage an event where people can drink all afternoon in a parking lot before going inside to drink some more “& well, then you are operating one of the world’s biggest bars, not merely an athletic contest.

But if someone is operating a huge bar, then it needs to be run like a huge bar. If that means bouncers to keep order, a parking lot patrol to evict misbehaving tailgaters, plus breathalyzer tests before fans enter the stadium, so be it.

And yes, I’m serious.

Monday, the 49ers and San Francisco officials did their best to move the needle toward a better and safer atmosphere at Candlestick. The cops announced there will be DUI checkpoints outside Candlestick after every 49ers home date. Alcohol sales will be stopped in the fourth quarter or earlier. Parking lots will not open until four hours before kickoff. Tailgating will be banned once a game begins.

It’s still not enough.

Responsible bars do not serve drunk people. Why not a breathalyzer test at the Candlestick or O.co Coliseum gates? Not everyone would receive one. It would be similar to an airport security setup.

Already, each ticket holder receives a pat-down for weapons and/or bottles.

More and more people think that the way they behaved Saturday is exactly how they are expected to behave at NFL games. It’s what happens in low places. The league is trying to stop that. The league needs to try harder.