By A Mystery Man Writer
Minor League Baseball will expand trials of a new rule that allows players to challenge balls and strikes using an automated ball-strike system if they think the umpire missed the call.
MLB announces experimental rules to be tested for 2022 Minor League season
ABS system gets rigorous test at Futures Game
Robot Umpires Could Be Coming to MLB as Soon as 2024 - CNET
They're testing a ball/strike challenge system in the minor leagues - Bleed Cubbie Blue
Inside Baseball's Desperate Effort to Save Itself From Irrelevance - The Atlantic
Major League Baseball Finally Feels Vital Again
Bulls Begin ABS Challenge Games
Japan's Standardized Baseballs Are Popular With Pitchers - The New York Times
Explaining ball-strike challenge system