In 1885, the rules changed to allow bats to be flat on one side; starting in 1893, they had to be round: Rules · Playability · Field team · Batting team. The rules do not specify the location of the other seven players, except that, at the time the field of play is handed over, they must be positioned in fair territory and not in the space between the thrower and the receiver. In 1887, the rules changed so that batters could no longer call a pitch; and the strike zone was defined from shoulders to knees. Another fundamental principle of the rules of baseball is that a runner who was initially ruled out can later be declared safe, but once a runner is declared safe, he cannot be called on the same play, unless he exceeds the base.
If the ball, or any part of it, passes through the area, it is considered a hit; otherwise, it is called a ball. The most recent significant rule changes, which prohibit the use of steroids and other performance-enhancing substances, have been widely supported to protect the integrity of the game. This rule of permanent substitution contrasts with other sports, such as basketball, hockey and American football, that practice free substitution. Due to frequent and often radical rule changes during this early period, the modern era is generally considered to have begun in 1901, when the American League was also formed.
Before 1883, throwers were required to throw throws with their hands below the hips; in that year, the rule was changed to allow for deliveries at shoulder height. The Official Baseball Rules govern all professional play in the United States and Canada, including the World Baseball Classic. In 1854, representatives met to set rules for the Knickbockers, Gotham and Eagle clubs, according to the Vintage Base-Ball Association, another old-school baseball group. The re-entry of a replaced player to the game is a violation of the permanent substitution rule; if the defense has more than nine players on the field at any given time, the referee must determine who is the tenth player and that player is expelled from the game.
Some youth or fan leagues end a game early if a team has ten or more runs ahead, a practice officially known as the advantage rule (sometimes referred to as the leniency rule or kill rule). Pitchers replace each other just like any other player (see above), and the rules don't limit the number of pitchers that can be used in a game; the only limiting factor is the size of the team, of course. When he meets for office, the president or, in his absence, the vice-president, shall appoint an arbitrator, who shall keep the game in a book provided for that purpose and shall record all violations of the statutes and rules during the exercise. The baseball regulations of the National University Athletics Association (NCAA), in addition to regulating the games of the members of that organization, are also used in several other competitions involving college-age players.
Many baseball players, fans and managers consider the rules and traditions of professional baseball to be time-tested and almost sacrosanct.