MLB's 7-Year ABS Struggle Shows Even Clear Rules Resist Automation

A new study published on arXiv (May 2026) by Andrea Wen-Yi Wang, Waki Kamino, David Mimno, Karen Levy, and Malte F. Jung from Cornell University examines Major League Baseball's seven-year struggle to implement the Automated Ball-Strike System (ABS). The paper uses Science and Technology Studies (STS) frameworks to show that even a seemingly straightforward rule—defining the strike zone as a rectangular area over home plate—requires extensive translation and negotiation when encoded into technology. ABS was envisioned as an objective tool to call balls and strikes accurately, yet it took MLB from 2019 to 2026 to field a system that satisfied stakeholders including players, umpires, owners, and fans.

The researchers reveal that the 'ground truth' of the strike zone has always been contested: historical practice blended the rulebook definition with umpires' enforcement discretion. MLB's ABS had to reconcile this hybrid reality while operating within an existing ecosystem of human umpires, broadcast metrics (like Statcast), and fan expectations. The study argues that conventional evaluation paradigms—which focus on the gap between a formal rule and its technical implementation—are insufficient. Instead, systems should be assessed by how they are experienced in practice, accounting for power dynamics, trust, and the social context of enforcement. This work contributes to ongoing FAccT conversations about evaluating sociotechnical systems and cautions against assuming that clear rules lead to straightforward automation.