ML baseball has just had its trade deadline final day which should be called "trade day" as it is a day that is a frenzy of excitement, hope, expectation and hundreds of trades. It is far more exciting than their all-stars game/week or their draft.
Interestingly players can enter into contracts that say they cannot be traded without their agreement (Giancarlo Stanton has one). Which means players must get paid more than they otherwise would in exchange for the possibility of being traded. Given the later, why shouldn't/couldn't the NRL go down the road of clubs being able to trade players like this.