Baseball, like any other sport, has gone under many revisions to its rules throughout its history. The only statement you say has never changed that I can tell

Baseball, like any other sport, has gone under many revisions to its rules throughout its history. The only statement you say has never changed that I can tell is the bases have been 90 feet apart since 1840. Pitchers have not always pitched from 60' 6" from the plate and home run distance, park size from plate, varies even today. Interestingly the park sizes differ to try and keep the difficulty of a home run equal in lieu of differences in air pressure between locations. It is rumored the Red Sox added a bullpen to give their new recruit Ted Williams, who was a left handed batter, an advantage at home. https://www.forbes.com/sites/quora/2011/09/13/q-why-are-major-league-baseball-fields-not-standard-in-size/#16b67c9c57ac https://www.forbes.com/sites/quora/2011/09/13/q-why-are-majo... I hate to cite forbes but its hard to find source for something I've known by word of mouth.