THe mound was lowered in 1969 after the McClain 31 wins and Gibson's insane 1.12 ERA in a season he had 12 losses!!! Pitching got diluted as well with expansion teams Expos, Royals, Padres and the legendary Seattle Pilots entering MLB.I am not sure if it was after 1968 or 1969 but the mound was lowered after all the dominant pitch