I don't really want to jump to conclusions here, but it's hard to imagine it was particularly necessarily to break a professional basketball player's leg in a brawl where it's unclear what role he played.

Dave Zirin for The Nation:

Sefolosha’s damaged fibula comes after a season when NBA players spent last wintermaking statements against police violence, after the killings of Michael Brown and Eric Garner. It also comes at a time when police brutality is under an exacting microscope following the execution of Walter Scott by Officer Michael Slager in North Charleston, South Carolina. In the blinkered reality of the sports world, the big story is that the damage to Sefolosha has happened right when the Atlanta Hawks are about to enter the playoffs with the best record in the Eastern Conference, jeopardizing what has been a dream season. Now, unless they make a deep playoff run, it will be remembered as a dream trapped between nightmares; a squad whose season began under a cloud of racist controversy, with the ugly leaked interactions between owner Bruce Levenson and general manager Danny Ferry, and now ends under a similarly colored cloud.

How in the hell did the NYPD come to injure Thabo Sefolosha? One moment fellow NBA player Chris Copeland and Copeland’s girlfriend Katrine Saltara were being stabbed at a trendy Chelsea nightclub (both are in stable condition), then Sefolosha and his Atlanta Hawk teammate Pero Antic were being arrested for obstruction… and then a broken leg. As for how Sefolosha’s fibula was fractured, there is the police version of what went down and then there is Thabo’s version. Stunningly, several outlets including ESPN first printed the police’s version as fact. If nothing else, the death of Walter Scott should be a lesson to all of us that there is a chasm between what the police can say happened and the reality of a situation.

That's really the heart of it, isn't it? It's not all that easy to believe a police officer's account of how things happened after seeing what happened to Walter Scott and comparing that to the officer's account. For far too long the benefit of the doubt has gone to the police officer's report without any criticism whatsoever.

And here is the police version of events, as reported by ESPN:

Sefolosha was hurt Wednesday morning outside a Manhattan night club, where a police report states he was resisting arrest. Sefolosha was arrested along with teammate Pero Antic for interfering with efforts of local police to set up a crime scene following the stabbing of Indiana Pacers forward Chris Copeland.

The player's union is involved now, questioning the police account of events as well as why Sefolosha was held for several hours at the police station with a broken ankle.

Zirin:

We do have a videotape of what took place, but all it reveals is multiple police officers jumping the rail-thin 6'7" 220 pound Sefolosha. Ironically, or tellingly, his fellow-arrestee, Pero Antic, has an appearance we’ll describe as ornately terrifying. Tattooed, bald, seven feet tall and over 260 pounds, he is a Macedonian guy who happens to be white. Sefolosha is a Swiss guy who happens to be black. The terrifying seven-footer walked away and the guy from Switzerland was jumped. Whether or not racial bias was involved, the optics of this are very familiar to anyone who has followed the methodologies of the NYPD.

Indeed. Meanwhile, the Atlanta Hawks have lost their player for the rest of the season and the NYPD has an injury to explain.