Minor League Baseball: Rules & Regulations

Most of baseball's minor leagues follow Major League Baseball's rules and regulations. The 19 leagues that comprise the National Association of Professional Baseball Leagues, ranging in level from Rookie to Class AAA, all adhere to MLB regulations with the exception of a few tweaks. With players aiming to advance from the minor leagues to the majors, a general uniformity of rules is crucial.

  1. Field and Equipment

    • The distance from home plate to the nearest outfield fence in fair territory must be at least 250 feet. The preferred distances are at least 320 feet along the foul lines and at least 400 feet to center field. The pitcher's mound should have an elevation of 10 inches. The pitcher's plate must be 24x6 inches, at a distance of 60 feet, 6 inches from home plate. Balls must weigh between 5 and 5 1/4 ounces, while bats must be no more than 2 3/4 inches in diameter at the thickest portion and 42 inches in length. In the minors, hitters must wear a double ear-flap helmet at the plate. Hitters in the majors typically wear single ear-flap helmets.

    Game Duration

    • Games consist of nine innings, but may go longer in case of a tie score. A game can have fewer than nine innings if the home team leads going into its half of the ninth inning or takes the lead before its half of the ninth inning ends. Games also may last fewer than nine innings if the umpire calls the game because of the weather or other reasons. Minor leagues may adopt a rule stating that doubleheader games will consist of only seven innings each. Minor leagues may also reduce a regular-season game to seven innings if it follows the continuation of a suspended game that has not reached the sixth inning.

    Batting

    • Batters must have at least one foot in the batter's box during an at-bat. An automatic strike is the penalty for leaving the box without an acceptable reason. In the minors, batters may leave the box in the act of swinging at a pitch or if the pitch forces them out of the box. A hitter also may leave in the act of feinting a bunt, when the defense tries to throw out a runner on the base paths or after a passed ball or wild pitch. The batter also may exit the box if the pitcher steps off the mound with the ball or the catcher leaves the catcher's box. However, hitters may never leave the dirt area around home plate during an at-bat unless the umpire calls "Time" so the fielding team can make a substitution or gather for a conference.

    Pitching

    • Baseball recognizes several variations of illegal pitches. The pitcher faces a severe penalty if he spits on the ball or on his glove, rubs the ball on his glove or clothing, applies any sort of foreign substance to the ball or in any way defaces the ball. In the minors, pitchers face ejection from the game and an automatic suspension of 10 games for such a violation. The same punishment applies if the umpire finds any foreign substance on the pitcher, even if the pitcher has not used the substance to doctor the ball.

    Statistics

    • When tracking statistics, the minors differ from the major leagues in a couple of respects. To determine the minimum number of plate appearances a batter needs to qualify for the season hitting title, minor leagues multiply a team's number of games by 2.7. In the majors, the multiplier is 3.1. For a minor-league pitcher to qualify for his league's pitching championship, as determined by earned run average, his number of innings must equal at least 80 percent of a team's number of games. In the majors, the number of innings must be at least 100 percent of the number of games.

    Independent Minor Leagues

    • A group of seven or eight minor leagues do not have a formal affiliation with Major League Baseball. These leagues follow the same basic rules for game play as Major League Baseball and its affiliated minor leagues. Any noteworthy rule differences involve roster sizes and player eligibility.