It has nothing to do with the officiating.
It has little to do with the coaching (can't say nothing).
It has everything to do with match ups.
Ross has a negative PER and winshares for the series. I don't think we need to look into any further metrics to determine that he's been awful, the eye test does that for us. Salmons hasn't been much better. Neither of them can guard Joe Johnson, but Casey literally doesn't have anyone else to throw on him with Fields out (aside from DD, who is getting abused when tasked with Johnson). In a close series between evenly matched teams, one matchup is enough to swing a series (Houston's inability to deal with Aldridge without killing their offense by playing Asik is a perfect example).
In contrast, the Raps have been completely unable to take advantage of the Nets playing small because their PFs can't post up effectively. Ditto Jonas with the Nets' bigs, though this is a baffling combination of coach, players and foul trouble conspiring to keep the ball out of his hands.
In other words, the Nets have been able to successfully exploit their matchup advantages while the Raps have not. You can blame that on coaching if you like, but that's not going to make Terrence Ross taller or suddenly give Amir a strong post game.
It's often said that in the NBA, the team with the best player in the series usually moves on. Well, as much as Raps fans don't want to hear it, Joe Johnson has been the best player in the series, and it's due entirely to matchups. And if he's the best player on the floor in game 7, the Raps are going to be in serious trouble.