Actually what the article states is that the NFL player salaries are about 56% of league revenues, MLB salaries about 58% of league revenues and the NHL salaries are at about 54% of league revenues.
The NBA salaries, as compared to all three other profitable overall sports league is right in line. In all other 3 profitable American sports leagues the players receive 54-58% of the league revenues. MLB and the NHL have significant revenue sharing in place. The NFL does as well though part of that lockout is about revenue sharing as well. The NBA revenue shares less than any sports league in America.
This needs to be resolved for the owners to get it to the point of every team being on an equal playing field without trying to decrease the players' share of revenues to a ridiculously lower level than that of the other three leagues that are all profitable and all have some form of significant revenue sharing.
I think it is tough to compare the NBA to MLB and the NFL.
The NFL has a much more balanced system, because of the massive National TV deals, which are shared evenly among the teams, and does not leave room for individual local TV deals that can vary dramatically from team to team that you have in the NBA, MLB, and NHL. That allows each team to have more of a fixed income level, so you don't have dramatic differences between teams.
In MLB, you have just a handful of teams paying a huge percentage of the salaries. When you have 3 or 4 teams with salaries well over $100 million, and then a bunch of teams less than $50 million, it really throws off the balance. But, in baseball, they can get away with this, because of the nature of the sport, and more importantly because of the very team centric rookie contracts which allows small market teams to keep young stars on relatively cheap deals for much longer than any other major sport.
The NHL on the other hand is comparable. They work at a lower number though, which makes it easier to control. And I think if the players will agree to a hard cap like the NHL, then the percentages could be comparable.