Probably the largest (and most controversial) change in baseball was the adoption of the DH by the AL in the 70s. For a full history of rule changes in basebal

Probably the largest (and most controversial) change in baseball was the adoption of the DH by the AL in the 70s. For a full history of rule changes in baseball: http://www.baseball-almanac.com/rulechng.shtml http://www.baseball-almanac.com/rulechng.shtml