If it weren't so sad and depressing, it would all be fairly laughable. The New York Red Bulls and New York City FC played their third and final regular season derby game in the first year of their Major League Soccer rivalry on Sunday, but just as much attention went to a pre-game brawl between the teams' respective fans.

Fans clashed outside of a Newark Irish pub and an Associated Press reporter happened to be there to record the brief exchange.

In New Jersey and immediately encounter crowd trouble ahead of the New York derby (Red Bulls-City). Video: pic.twitter.com/slY3hYn5aM — Rob Harris (@RobHarris) August 9, 2015

The brief flurry of images seem to depict some shoving, a few punches thrown and a sandwich board and some garbage bags wielded as weapons. Then, a single police car emitted a wail, which broke the whole thing up. One side fled – apparently New York City FC fans – as the other side – allegedly Garden State Ultras, a New York Red Bulls supporters group who considers the pub in question its home turf – started a chant of "Who Are Ya" in affected English accents.

And that was really all there was to it.

But if this amounted to no more than a brief scuffle, it was nevertheless rank and intentional hooliganism. It was Anglophilia funneled through soccer. The fetishization of another country's faded culture of sporting violence. And the implications are far more significant than the fight itself.

The English Premier League was once a bulwark of this sort of stuff – not to mention stampedes and all-out riots. It has long since rooted out fan violence after a concerted and lengthy campaign to sanitize its stadiums – although it should be noted here that the sharp rise in Premier League ticket prices seemed to have done much of the job on the league's behalf. Now, MLS could have the same sort of problem on its hands – growing pains in the climb to real relevance, perhaps.

Fan violence isn't entirely new to the league, though. There have been sporadic incidents before, like when San Jose Earthquakes supporters attacked a Portland Timbers fan in April 2013. But for the most part, any bluster and posturing between fans is innocuous enough. I once heard a D.C. United fan declare that he had half a mind to go punch a man who had shown up to their tailgate donning a Seattle Sounders jersey, the opponent for that night's game. But then he just carried on making his tifo. The bark is very rarely followed by a bite.

This incident, however, is different. This is real fan violence, within walking distance of what was a soon-to-be packed stadium. And it's deeply disconcerting.

One of the league's big selling points is its fan culture. The singing, the chanting, the flags and banners and oversized tifo, all on show in stadiums every weekend from spring to fall. They set Major League Soccer apart from other stateside fan experiences in a crowded space. The often electric atmosphere is organic, rather than being piped in through a sound system. A growing customer base has shown its appreciation of this product through an average attendance that, at more than 21,000, is up a good 10 percent over last year's record of 19,149.

The passion and pageantry coexist harmoniously with families, who still make up a huge part of the league's live attendees, by virtue of the almost total lack of violence, or even the threat of it. Aside from being plain wrong, what happened in Newark on Sunday is bad for business and potentially ruinous to the league in the long run if it isn't checked immediately. There are examples aplenty of soccer leagues whose attendances cratered after hooliganism became systemic and uncontainable.

As a league, MLS has made real strides in recent years. Its viability is now finally above question, even if it still claims to lose money. And as far as sporting entertainment goes, it's probably one of the better value-for-money experiences out there. But try convincing a family with young children and an appetite for live soccer to spend its disposable income on the local MLS team when word gets out that a wrong turn on the walk to the stadium could land you in the middle of some drunken, loutish standoff.

Let's be fair here. The league's many and invariably pleasant and welcoming fan groups universally say they condemn violence. I once stood amid the Philadelphia Union's dominant Sons of Ben fan group when a member threw an empty plastic bottle on the field during the game. He was instantly reprimanded by the exasperated leadership. The leaders of these proliferating groups are savvy and well-intentioned and do it for no other reason than their devotion to their local team and soccer scene.

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