The fact is, the way people stream games for free, the NBA would be better off offering a Pandora-like/Hulu-like service where it is essentially free, but the advertising is geared toward the region of the viewer (rather than just Boston, since most games seem to come through NBCSN Boston). There could be pay options available, like: ability to replay games at your leisure without commercials or pausing during games.
There's just no way to stop people from streaming games. And even if you do have LP - but not a cable/live tv subscription - you are going to need to stream many games anyway since there are so many national games.