Umpires were now required to put new balls into play whenever the current ball became scuffed or discolored. This rule change was enforced all the more stringently following the death of Ray Chapman, who was struck in the temple by a pitched ball from Carl Mays in a game on August 16, 1920; he died the next day.
Umpires were now required to replace worn-out baseballs, following a rule change that was enforced more strictly after Ray Chapman's death.