Contracts do carry weight, otherwise why bother with them, the league has zero influence over the law, league or not a contract is a legally binding document.
I can’t comment on the specifics because l don’t & neither does anyone else writing here know the specifics, we don’t even know if this is the issue. Having said that, contracts most certainly can be challenged or enforced, it all depends on individuals & the circumstances. What we do know is within the world of professional sports, players have regularly been held to ransom within their respective teams. If both parties want to break the contract amicably of course, both can walk away, imagine though your boss is an arsehole, we all know there are many, you don’t have to look hard, in fact we’ve all got one. Imagine then you’ve really upset that boss & in retaliation, he’s happy to loose a bit of money to keep you smiling in public, doing boring training sessions and held off playing the game you love, knowing you hate every second & the only get out would cost you far more than you could afford.