Owners willingly sign the contracts, therefore athletes deserve to make exactly what they earn. A market price/wage is automatically deserved, because by definition it's something that both sides agree on. Any other definition of a "fair/deserved" price/wage is arbitrary and illogical, in my opinion.
This is a capitalist view, obviously, but really the only two options for setting a price/wage is:
a) The free market
b) The government (elected, dictator, whatever) setting the price/wage, arbitrarily
c) Some combination of the two, like the government altering prices so they're higher (say, through excise taxes) or lower (say, through subsidies)
And to me, the free market is far more "fair" than anything where the government is involved, as a free market price/wage is by definition the two sides agreeing on a price/wage that makes them both happy, not some ruler with the threat of force telling you how something will be. Plus, free markets (or at least relatively free markets) have consistently been shown to be far more stable than highly controlled markets/economies.
Btw, I consider the NHL negotiating with the players association on salary caps to be part of the free market. Sure teams compete against each other on the ice, but the NHL as a whole is an organization with the goal of making money, all teams combined will try to make as much money for the league as a whole as possible, they're not trying to put each other out of business like truly separate, competing companies do, they're openly working towards a common goal. Teams within the NHL coming together to set limits on wages is not much different than, say, a large holding company like Berkshire Hathaway having policies related to wages of the employees of the various companies they control. If the employees don't like it, they can negotiate for better terms (such as CBA negotiations in the NHL), or simply quit and work elsewhere, this is true in the NHL just as it is true with any other business.