Robots behind the plate? Why baseball's challenge system is whole new ballgame for some umpires

Cincinnati Reds slugger Eugenio Suárez didn't like what he saw when a pitch he was thrown in the sixth inning was called a strike in a game earlier this season.

So he challenged the call by home plate umpire C.B. Bucknor using the new Automated Ball-Strike (ABS) challenge system. The call, made during the March 28 game against the Boston Red Sox, was overturned and the called strike became a ball.

The same thing happened on the next pitch, as Suárez again challenged and again had a called third strike converted into a ball. He wasn't the only player to successfully challenge two calls that game — his teammate Will Benson did, too.

This is the new world of Major League Baseball (MLB) where hitters, catchers and pitchers can challenge balls and strikes using the ABS challenge system that measures pitches against the strike zone for each batter in real time. In short, home plate umpires are having to adjust to the fact that a robot can check their work at any point in a game.

The ABS system calculates if a pitch falls within a two-dimensional strike zone that is calibrated to specified parameters for each batter — all the players were measured this year.

In each case, the strike zone is the full width of the plate, with the top of the strike zone set to 53.5 per cent of a given player's height, and the bottom at 27 per cent.

And that's what determines if the challenged call stands or not.

There are rules surrounding the challenges, including a requirement that they be made within two seconds of an umpire's call.

Each team gets two challenges during regulation play. If the challenge is successful, they retain it. If it isn't, they lose that challenge. So, if teams aren't strategic about when they use the challenges,