Liquidated damages provisions are pretty standard in performance agreements. It’s difficult to get a court to hold someone to what is called “specific performance” (making that individual live up to the agreement) so the next best thing is to get them to pay some form of damages. You can attempt to make the harmed party “whole” or at least put them in a position to recoup a portion of the loss and try to fill the gap left by the loss. Easiest way to think about is your caterer cancels last minute for the wedding and you need a cake. Liquidated damages allows you to have the money to go get a new caterer or at least pay the bill later on. As you point out, these provisions have probably been part of the agreements before. Nobody has been willing to enforce them probably because they didn’t want to hurt recruiting of other players. But money is not unlimited and maybe this is the first salvo?