MLB History By LSMAY77 Apr 17, 1953 Players remove the glove from play Apr 17, 1959 Regulations were set up for ballpark lengths 325-400-325 ft Apr 17, 1968 Anti- spitball rule Apr 17, 1969 Strike zone is shrunken to the armpits to the kneecaps Apr 17, 1969 The pitchers mound is dropped 5 inches Apr 17, 1969 Save rule was put into effect Apr 17, 1971 All major League players are required to wear helmets Apr 17, 1973 the rule on glove size was minutely outlined for standardization Apr 17, 1973 The american League began to use DH Apr 17, 1973 DHs were put to use Apr 17, 1974 the save rule was rewritten Apr 17, 1974 Min standards for championships were rewritten Apr 17, 1975 the ball was permitted to be covered with cowhide because of the shortage of horses Apr 17, 1975 The save rule changes again Apr 17, 2008 Instant replay is permitted