This is a great article by Henry Abbott about what decreasing players' salaries means.
He suggests that by paying them less, they have the power because they are worth much more than what you are paying.
In order to account for that disparity, they can demand things like specific teammates.
In contrast, if a player is making more money than he is worth, the owner can demand things from the player to account for that disparity.
It's a fascinating article and a must read in my opinion.