Will try to make this short and sweet without any tired millionaire vs billionaire verbiage.
There are anti monopoly rules, the US gov't doesn't like monopolies or even duopolies being created (see ATT's attempt to buy T-Mobile) and regulators love to tell them what they can do (look into who gets final say when your local phone company, or electric utility want to raise your rates) if they can't be broken. However Pro sports however gets a free pass, the anti trust exemption. If you want to get into more on the legal history check this out: http://www.thesportjournal.org/article/role-antitrust-laws-professional-sports-industry-financial-perspective
In this case of NBA vs the NBA players association the blame is quite one sided and simple to administer. Take the jump for the cold blooded reality of it.
When facing a monopoly there are only three ways to fight:
1) implicit or explicit destruction of the business in question or to put it plainly, "If I can't have it, I will make sure you can't have it either." That can't really happen here, the players can't do any material damage, but they can easily be replaced.
2) You can get the government to act in your favor. The exemption precludes that and politicians are not going to gain any votes from getting involved in this.
3) You can look to start a competing business. Like the ABA in hoops and the USFL in football. Unfortunately for the players they either didn't care to look into this or didn't like what they saw when they did.
The player's union is up against a larger, stronger, better capitalized group with legal support and have no strategy. None. Hope? The impassioned back room pleas of Mark Cuban and Mickey Arison? C'mon.
The Players Union brought to a butter knife to a gun fight. That is where the blame lies.