So you cited a bunch of aging, ring-chasers who would be out of the league as the "middle class"? Well, now we're just being silly.
The NBA splits almost the same amount of money as baseball (3-4B) over half the number of players. Part of why the league has so many teams pushing the cap (and well above it) is that basketball teams know that even letting average dudes hit free agency is a recipe for losing them without any compensation. They'd rather exceed the cap and price-match salaries in trade than lose them. That's why guys like Taurean Prince, Michael Beasley, and Hernangomez are making significant money in the NBA (just to name three recent Wolves). Those guys are the middle class and they are getting PAID. Go ahead...name three more teams not named the Thunder and I'll find hefty contracts they gave out to bench players. Same goes for the NHL too BTW - where plenty of third liners or blue collar D-men are being paid 3-6M. Right Victor Rask? (I admit, lumping Rask in with third liners is deeply unfair to third liners, my apologies)
And why is that? Well, unlike baseball, teams in the NBA and NHL know they can't just let their players "test the waters" and then limp back for a deal later. In leagues with a floor, middle class players are not low-balled or leveraged by a low number of suitors. Floors, and the spending incentive they create and the corresponding need to retain assets, create a more competitive bidding process. Or force trades to avoid losing players for nothing. It may not happen instantaneously, but instead creates a culture in which everyone is expected to be competing and paying players. That has a trickle down effect.
So does the reverse, as MLB keeps demonstrating.