MLB’s first trade-deadline rule followed the Red Sox sale of Babe Ruth to the Yankees.
Boston’s sale of Ruth became public in January 1920 after the transaction was arranged at the end of 1919. The American League adopted baseball’s first strict trade-deadline rule in 1920, partly in reaction to the competitive imbalance created when financially stronger clubs could acquire prominent players from rivals.
Ruth’s move was especially consequential because he was already an exceptional pitcher and was about to become baseball’s dominant home-run hitter. With New York, he transformed the Yankees into a major force and helped usher in the sport’s home-run era. Boston, meanwhile, entered an infamous championship drought later associated with the “Curse of the Bambino.”
The transaction is often called a trade in casual discussion, but Boston primarily sold Ruth’s contract and reserve rights for cash and financial consideration. That technical distinction does not change the quiz answer: the player connected to the rule’s origin story was Babe Ruth, not another Yankees or Red Sox star.