Robot umps, bigger bases and more: MLB announces experimental new rules for minor leagues

After a full season off due to the coronavirus pandemic, the minor leagues are returning. Under MLB's complete control. With 40 fewer affiliated teams.

Sweeping changes hit Minor League Baseball in its dormancy, due to issues both caused and exacerbated by the pandemic and issues completely independent of it. The upshot is that the minors will look quite different as they come back, and MLB announced Thursday a few more reasons it will look even more different.

A set of experimental rule changes will be instituted up and down the minor leagues in 2021, with all four levels each seeing a different tweak or tweaks to how the game is played. Here's what those will be, and what MLB is hoping to see as it tries to boost TV interest of its product:

Triple-A: Larger bases

The rule change: The size of first, second and third base will all be increased from 15 inches square to 18 inches square.

What MLB wants to see: The MLB primarily cites a reduction in injuries and collisions for the change, the idea being more room on the bases means more room for runners to reach base without running into or onto defenders. It's also hoped that slightly larger bases will mean slightly increased success on stolen base attempts.

Double-A: Four infielders in the dirt

The rule change: Defenses will be required to have a minimum of four players standing with both feet on the infield dirt. Another change requiring two infielders to be positioned on each side of second base could also be institute for the second half of the season.

What MLB wants to see: This is the boldest step yet in Rob Manfred's efforts to kill the defensive shift, which the commissioner has long criticized as too disadvantageous for offenses. Some believe shifts are merely a natural evolution of a sport in which pull-happy offenses have failed to adjust, but Manfred's the one in charge, so the minors will take this baby step now with a much bigger one potentially incoming.

High-A: Pitchers can't pick off from rubber

The rule change: Pitchers will be required to step off the rubber prior to throwing to any base. Failure to do so will be a balk.

What MLB wants to see: In a few words: more stolen bases. In a few more words: many, many, many more stolen bases. The larger bases in Triple-A could lead to a modest increase in stolen bases; this should cause them to skyrocket.

MLB notes that it implemented a similar rule in the Atlantic League in 2019, leading to "a significant increase" in both stolen base attempts and stolen base success rate. Of course, that wasn't the only effect of the change. As Yahoo Sports' Hannah Keyser documented, it drove pitchers nuts. The effects are especially felt by left-handers, who will no longer be able to use their leg lifts to keep runners honest at first base. Once a pitcher lifts his leg, it's a green light.

ALLENTOWN, PA - APRIL 30: Pitcher Drew Anderson #40 of the Lehigh Valley Iron Pigs gets set to pitch as a pitch clock counts down during the second inning of a AAA minor league baseball game against the Syracuse Mets on April 30, 2019 at Coca Cola Park in Allentown, Pennsylvania. (Photo by Rich Schultz/Getty Images)
Pitch clocks are likely coming to MLB. (Photo by Rich Schultz/Getty Images)

Low-A (both leagues): Cap on pick-off attempts

The rule change: Pitchers will be limited to a total of two pick-off attempts or step-offs per plate appearance. If a third attempt is made, it's a balk as long as the runner makers it back to the base safely. MLB is also considering lower the cap to just one attempt.

What MLB wants to see: Similar to the change directly above, MLB wants more stolen bases. The dance between pitchers and runners will suddenly have a cap imposed, which figures to increase activity on the basepaths. The decline of the stolen base has been lamented for years, and MLB is trying out three different rules to reverse that.

Low-A (Southeast): Robot umps

The rule change: An automatic ball-strike system will be tested in select games to assist home plate umpires.

What MLB wants to see: The league has been playing around with this for years in the Atlantic League and Arizona Fall League, and it almost feels like the league is just ironing out the kinks before instituting robot umps at this point. It's unclear if umpires will be required to relay the strike call or will only receive them as a strong suggestion. Either way, there's a good chance Angel Hernandez won't be able to hurt you anymore.

Low-A (West): Pitch clock

The rule change: New regulations will be added to the pitch clocks to enforce time limits on delivery of pitches, inning breaks and pitching changes.

What MLB wants to see: MLB has already used pitch clocks in spring training, Triple-A, Double-A, High-A and the Arizona Fall League going back to 2014, so this is an expansion of another change that feels inevitable at this point. It infuriates pitchers, but that's the sacrifice Manfred is willing to make to improve pace of play.

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