The collective bargaining agreement is the agreement between Major League Baseball and the Players Association. It determines everything from free agency, salary arbitration, luxury tax as well as the disabled list, paternity list, bereavement list and even the system the commissioner must follow to make rule changes such as a pitch clock.
The players union and their agents are especially upset at how difficult it has been for free agents to make new deals. In many cases, players have had to settle for contracts that are much shorter and salaries that are much lower than would have expected just two years ago.