<P> Although the de facto enforced strike zone can vary, the official rules (Rule 2.00, A STRIKE (b)) define a pitch as a strike "if any part of the ball passes through any part of the strike zone ." </P> <P> A batter who accumulates three strikes in a single batting appearance has struck out and is ruled out (with the exception of an uncaught third strike); a batter who accumulates four balls in a single appearance has drawn a base on balls (or walk) and is awarded advancement to first base . In very early iterations of the rules during the 19th century, it took up to 9 balls for a batter to earn a walk; however, to make up for this, the batter could request the ball to be pitched high, low, or medium . </P> <P> While baseball rules provide a precise definition for the strike zone, in practice, it is up to the judgement of the umpire to decide whether the pitch passed through the zone . </P> <P> Rule 9.02 of the Official Baseball Rules states that objections to judgment calls on the field, including balls and strikes, shall not be tolerated, and that any manager, coach, or player who leaves his dugout or field position to contest a judgement call will first be warned, and then ejected . </P>

Who calls the pitches in major league baseball