BA Newsletter: Get Analysis, Rankings Delivered To Your Inbox!

Arizona Fall League Will Feature Several Experimental Rule Changes In 2021

AFL Champions Billmitchell
(Photo by Bill Mitchell)

Pitch clocks, shift restrictions and more changes are coming to the Arizona Fall League.

Major League Baseball confirmed Thursday that the AFL will feature most of the experimental rules changes that were introduced into the minor leagues this year.

Pitchers will be subject to a 15-second pitch clock and limited to two pickoff attempts per plate appearance, infielders will be required to remain in the dirt with two positioned on each side of second base and the size of the bases will be increased.

The automated ball-strike system, which the AFL experimented with in 2019, will be used in games played at Salt River Fields.

MLB introduced each rule at different levels of the minors for the 2021 season. The AFL presents an opportunity to see what games look like with all of the rules changes in place simultaneously.

The 15-second pitch clock was introduced in the Low-A West this season on June 8, five weeks into the season. Nine-inning games prior to the introduction of the pitch clock lasted an average of 3 hours, 2 minutes. Nine-inning games after the introduction of the pitch clock averaged 2:41, as The Athletic’s Jayson Stark first reported. The introduction of the pitch clock also corresponded with an increase in offense throughout the league.

The limit of two pickoff attempts per plate appearance was also introduced in Low-A this season. The number of stolen base attempts at the level rose from 2.3 per game in 2015-19 to 3.1 per game this year with the limit in place, according to MLB.

The rule governing the positioning of infielders in an attempt to limit shifting was introduced at Double-A this year. All four infielders were required to remain in the dirt for the first half of the season and two infielders were required to remain on either side of second base during the second half.

The rules resulted in no significant change in batted-ball outcomes at Double-A, according to Major League Baseball executive vice president of baseball operations Morgan Sword. Nonetheless, MLB will apply the rules in the AFL to gather additional data.

The larger bases were introduced at Triple-A this year, with the size of the bases increased from 15 inches square to 18 inches square. The change led to a slight increase in the success rate of stolen base attempts and led to a decrease in the number of collisions and injuries sustained around the bag.

The AFL begins on Oct. 13 with the new rules in place.

Editor's Note: The date pitch clocks were implemented in the Low-A West has been corrected.


Baseball America 'Insider' Mailbag Volume 2: Valuing Pitchers, Golden Age Of Shortstops & More

Today in the Baseball America Insider Mailbag we're looking at the changing world of how pitchers are valued, a golden age of shortstops and Rule 5 fever.

Are you a member?

In order to access this exclusive content you must have a Baseball America Account. 

Login or sign up  

Additionally, you can subscribe to Baseball America's newsletter and receive all of our rankings, analysis, prospect insight & more delivered to your inbox every day. Click here to get started. 

of Free Stories Remaining