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Pitching-rubber shift part of 2021 Atlantic League experimental rules

Atlantic League 2018MLB and the Atlantic League are moving forward with new experimental rules for the 2021 season, including a move of the pitching rubber a foot back and the loss of the DH when a starting pitcher leaves the game.

The new rules will be implemented in two stages for the 2021 season: full season and half season. The tinkering with the DH rules will be run during the entire 2021 Atlantic League season and ties the DH position to the starting pitcher in the so-called “Double Hook” rule change. Once a team’s starting pitcher is replaced, the team will lose its designated hitter for the remainder of the game. The team will be required to use a pinch hitter, or the relief pitcher will bat. According to MLB, the rule aims to incentivize teams to leave their starting pitchers in longer, increase the value of starters who can work deeper into games and increase the strategic element in the late innings of a game. So for those orgs who monitor starting pitching and keep them to strict pitch counts: too bad.

In the second half, the pitching rubber will be moved back 12 inches to 61’6”, giving batters more time to react to pitches. According to MLB, the expectation is that more reaction time will help batters make contact more frequently, putting more balls into play, and creating more action in the game. The science from MLB: The reaction time on a 93.3 mph fastball (average velocity in 2020) thrown from 61’6” is approximately equivalent to a 91.6 mph fastball (the average fastball velocity in 2010) thrown from 60’6”. The move should also cut down on the strikeout rate., which has gone from from 16.4 percent of plate appearances in 2005 to an all-time Major League record 23.4 percent in 2020. 

To address the elephant in the room: MLB expects the change to be safe for pitchers, as it does not require the pitcher to alter pitching mechanics and there is no evidence of increased injury risk. Research from The American Sports Medicine Institute (“ASMI”) conducted a study in October of 2019 that measured the impact of pitching distance on biomechanics studied the mechanics of high-level collegiate baseball players throwing from distances of 60’6”, 62’6”, and 63’8”. No significant differences in key measures of rotational motion (kinetics) or acceleration (kinematics) were observed among the varying pitching distances, according to MLB. Such tinkering with the mound is not unheard-of in baseball; several times in the past the mound has been moved or lowered, though not since 1969.

In addition, robot umps will be used again the Atlantic League in the form of to upgrade the TrackMan tracking technology that will be used during the 2021 season to project and measure pitches. 

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