Major League Baseball (MLB) announced today the testing of a variety of experimental playing rules at various levels of the Minor Leagues during the upcoming 2021 season. These experimental playing rules have been approved by the Competition Committee and the Playing Rules Committee. MLB will closely monitor and analyze the impact of each rule change throughout the 2021 season and report to Clubs on their effects for further analysis. Consistent with the preferences of our fans, the rule changes being tested are designed to increase action on the basepaths, create more balls in play, improve the pace and length of games, and reduce player injuries.

Below is a summary of the experimental rules that will be tested during the 2021 Minor League season, which will vary by level of play:

• TRIPLE-A (LARGER BASES): To reduce player injuries and collisions, the size of first, second and third base will be increased from 15 inches square to 18 inches square. The Competition Committee also expects the shorter distances between bases created by increased size to have a modest impact on the success rate of stolen base attempts and the frequency with which a batter-runner reaches base on groundballs and bunt attempts.

• DOUBLE-A (DEFENSIVE POSITIONING): The defensive team must have a minimum of four players on the infield, each of whom must have both feet completely in front of the outer boundary of the infield dirt. Depending on the preliminary results of this experimental rule change, MLB may require two infielders to be positioned entirely on each side of second base in the second half of the Double-A season. These restrictions on defensive positioning are intended to increase the batting average on balls in play.

• HIGH-A (“STEP OFF” RULE): Pitchers are required to disengage the rubber prior to throwing to any base, with the penalty of a balk in the event the pitcher fails to comply. MLB implemented a similar rule in the second half of the Atlantic League season in 2019, which resulted in a significant increase in stolen base attempts and an improved success rate after adoption of the rule.

• LOW-A (PICKOFF LIMITATION, PITCH TIMER, AND ABS):

o ALL LOW-A LEAGUES: Pitchers will be limited to a total of two “step offs” or “pickoffs” per plate appearance while there is at least one runner on base. A pitcher may attempt a third step off or pickoff in the same plate appearance; however, if the runner safely returns to the occupied base, the result is a balk. Depending on the preliminary results of this experimental rule change, MLB will consider reducing the limitation to a single “step off” or “pickoff” per plate appearance with at least one runner on base.

o LOW-A SOUTHEAST: In addition to the limitations on step offs/pickoffs, MLB will expand testing of the Automatic Ball-Strike System (“ABS”) that began in the Atlantic League and Arizona Fall League to select Low-A Southeast games to assist home plate umpires with calling balls and strikes, ensure a consistent strike zone is called, and determine the optimal strike zone for the system.

o LOW-A WEST: In addition to the limitations on step offs/pickoffs, following successful pace of game rules testing among Florida State League teams in 2019, on-field timers (one in the outfield, two behind home plate between the dugouts) will be implemented to enforce time limits between delivery of pitches, inning breaks and pitching changes. The on-field timer used in Low-A West will include new regulations beyond the system currently used in Triple-A and Double-A to reduce game length and improve the pace of play.

“We are listening to our fans. This effort is an important step towards bringing to life rules changes aimed at creating more action and improving the pace of play,” said Michael Hill, MLB Senior Vice President of On-Field Operations. “These experimental playing rules have been approved by the Competition Committee and the Playing Rules Committee to be tested and analyzed in a highly competitive environment.”

"These experimental rules are designed to put more balls in play, create more excitement on the basepaths and increase the impact of speed and athleticism on the field,” said Raúl Ibañez, MLB Senior Vice President of On-Field Operations. “As another important goal of the rules approved by the Competition Committee and the Playing Rules Committee, we expect the new larger bases to increase player safety. We look forward to testing these rules in the Minor Leagues.”

“The game on the field is constantly evolving, and MLB must be thoughtful and intentional about progressing toward the very best version of baseball – a version that is true to its essence and has enough consistent action and athleticism on display to entertain fans of all ages,” said Theo Epstein, Consultant to MLB. “These rules experiments will provide valuable insight into various ways to create a playing environment that encourages the most entertaining version of the game. What we learn in the Minor Leagues this year will be essential in helping all parties chart the right path forward for baseball.”

MLB also continues its three-year partnership agreement with the Atlantic League of Professional Baseball (ALPB), which was announced in 2019. This partnership agreement allows MLB to test and adjust experimental playing rules and changes to equipment each season. Any new experimental playing rules for the 2021 season will be announced in the coming weeks.