Major League Baseball will test two new rules in the Atlantic League in 2021: the "double hook" designated hitter rule and moving the pitching rubber back 1 foot, the league announced Wednesday, according to MLB.com's Anthony Castrovince.
"Fans, players, and many others in the baseball community have expressed an interest in seeing more regular action on the field," said MLB rules consultant and former general manager Theo Epstein.
"Therefore, it's important that we use the 2021 season to explore various ways to create more frequent contact - and the increased action and athleticism on display that will follow," he continued.
The "double hook" rule is a compromise between the American League and National League styles of play. Once a team's starting pitcher is replaced, the club will lose its DH for the remainder of the game. The squad will be required to use a pinch hitter or let a reliever take the at-bat.
The aim of the "double hook" is to incentivize teams to leave starting pitchers in longer, thus increasing the value of hurlers who can work deeper into games and also putting more emphasis on late-inning strategy. The rule is a response to the increased number of relievers and openers currently used throughout the league.
The "double hook" will be in effect for the entire 2021 Atlantic League season.
The Atlantic League will also experiment with the pitching rubber, moving it back a foot to 61 feet, 6 inches from home plate. The purpose of the change is to give hitters more time to react to pitches, increasing their chances of making contact.
The reaction time on a league-average fastball (93.9 mph) thrown from 61 feet, 6 inches is equivalent to a 91.6-mph fastball thrown from 60 feet, 6 inches, according to MLB.
The MLB strikeout rate has climbed for 15 consecutive seasons with the mound at 60 feet, 6 inches, reaching an all-time record in 2020 of 23.4%.
The pitching-rubber move won't occur until the second half of the Atlantic League season, providing an opportunity to compare the first- and second-half statistics.
MLB and the Atlantic League have maintained a partnership since 2019 to examine the effects of various rule and equipment changes before potential implementation in MiLB or the bigs.
"The Atlantic League is an important step in the pipeline for potential rule changes at the major-league level, and we look forward to seeing them brought to life in a competitive environment," said MLB executive vice president of baseball operations Morgan Sword.