Robot umpires are coming to MLB. Here's how they work

Modern stadiums are now outfitted with sophisticated camera arrays that track every pitch trajectory with immense precision. These systems determine if a ball crossed the home plate within the predefined vertical and horizontal bounds of the strike zone. During initial development, umpires utilized discreet ear buds to receive instantaneous feedback, hearing either “ball” or “strike” directly from the software. They would then relay this decision to players and fans through classic hand signals. This initial method laid the groundwork for the more nuanced, interactive approach being implemented across the major leagues today.

The current challenge system introduces a strategic layer to the game. While human umps retain primary responsibility for calling every pitch, each team is granted two challenges per contest. Teams that successfully navigate their challenges retain them, mimicking the mechanics of existing video replay protocols, which first gained traction for home runs in 2008 and saw widespread expansion by the 2014 season. If a team exhausts its initial allotment, they receive one additional attempt per extra inning, keeping the late-game stakes high.