# Robot umpires reduce favorable calls for star players in Korea KBO's automated ball-strike system led to performance drops for top hitters. - **Source:** [Popular Science](https://brifing.si/source/cc3d313a-759c-4802-b881-fc8585f35ef9) - **Published:** 2026-07-14 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/d1004d6d-894a-48ca-be7f-d05e485ea762 ## The Rise of Robot Umpires The Korea Baseball Organization (KBO) implemented the Automatic Ball-Strike system (ABS) in the 2024 season. This system uses sensors and camera arrays to determine whether a pitch crosses the strike zone. Human umpires receive ABS data and make calls based on this information. The goal is to reduce bias and ensure fairer decisions. ## Performance Decline for Star Hitters Researchers at the University of Michigan found that top-ranked hitters performed worse after ABS was introduced. These players drew fewer walks, struck out more, and reached bases less often. The findings suggest that umpires may have previously favored star batters in borderline calls. ## No Significant Change for Pitchers The study noted that ABS had less noticeable effects on famous pitchers. This could be due to more variable pitcher performances or fewer opportunities to show decline. The results indicate that ABS impacts may vary by position. ## How Umpire Calls Shape the Game The research showed that ABS changed umpire decisions without altering players' overall performance. This highlights how favorable calls for star players previously influenced game statistics. ## Bias Beyond Sports Researchers pointed out that high-status bias isn't limited to baseball—it's prevalent in professional and educational settings too. Systems like ABS could help reduce such biases in various fields. ## The Future of Human Umpires Experts don't expect robot umpires to completely replace humans, as subjective decisions still require human judgment. However, systems like ABS can play a crucial role in enhancing fairness in sports. ## Sources covering this story - https://www.popsci.com/technology/robot-baseball-umpires-korea/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._