- Updated: April 2, 2026
- 2 min read
MLB’s Automated Ball‑Strike Challenge System Highlights Umpire CB Bucknor as Worst Performer
MLB’s Automated Ball‑Strike Challenge System Highlights Umpire CB Bucknor as Worst Performer
The newly implemented Automated Ball‑Strike (ABS) Challenge System has turned the spotlight on MLB umpire CB Bucknor, revealing a strikingly low accuracy rate that has resulted in a wave of overturned calls. In a season where technology is reshaping the game, Bucknor’s performance stands out as a cautionary tale for traditional officiating.
Since the ABS rollout, data shows that Bucknor’s strike‑zone calls were overturned over 40% of the time, the highest rate among all major‑league umpires. The system, which allows managers to challenge balls and strikes in real time, recorded 112 challenges against Bucknor’s calls, with 46% being successful.
These statistics have sparked a broader conversation about the future of umpiring. While many veterans argue that human judgment adds nuance to the sport, the ABS data suggests that consistency—and consequently, fairness—may increasingly depend on technology.
For a deeper dive into how the ABS system works and its impact on the league, visit our ABS System Overview. Additional analysis on umpire performance trends can be found in our Umpire Analytics section.
Read the original Verge article for full context: MLB ABS Challenge System Exposes CB Bucknor as Worst Umpire.
Andrii Bidochko
CTO UBOS
Andrii Bidochko is an AI entrepreneur and researcher focused on AI agents, reinforcement learning, and autonomous systems. He writes about the technologies shaping the future of machine intelligence, from frontier models and agent architectures to real-world AI applications.