I think Scott is well intentioned but wrong.
No way HD rights are different. The VP of the NHL is pushing for more HD - I don't think they'd object.
This isn't a bandwidth issue either. NESN-HD shows all hockey games in HD, but most (not all) are blacked out.
I have a hunch that we know more than Scott.
Again, be sure to read Satelliteracer's posts for great info.
Actually the territories for NBA, NHL, MLB are all different and that does effect some of this as it realated to blackouts, but not all of it. But it is absolutely possible for someone to have a blackout for a Denver team (for example) in one league and not for a Denver team from another league, depending on how the territories are laid out by the leagues.
I should have some news for you guys by end of today on the HD blackouts...stay tuned.