As the calendar turns to the final day of March, Laz Diaz has emerged as the league’s most scrutinized umpire. He currently sits at the top of the leaderboard with 12 total challenges against his calls. It has been a rough start for the veteran, who saw a small portion of his 247 total calls this season overturned.
The numbers don’t lie: Diaz 50% overturn rate highlights the growing pains of MLB’s new challenge era. Even with years of data from the minor leagues showing that over half of all challenges are typically upheld, veteran umpires are still finding the transition to the ‘Robot Ump’ era a difficult one to navigate.
Other umpires have also been heavily tested by the ABS challenge system early in the season. CB Bucknor and Adrian Johnson each have 8 challenges so far, with six and five overturned calls respectively.
The most challenged umpires in 2026
Some umpires have clearly felt the pressure when players challenge calls. It often shows on the home plate umpire’s face when they have to activate the microphone and announce that a batter or catcher has challenged a pitch, with even pitchers occasionally getting involved.
Derek Shelton discusses a call with umpires Laz Diaz (left) and Chris Segal (middle) (Jamie Sabau/Getty Images)
| Umpire | Challenges | Overturned calls |
| Laz Diaz | 12 | 6 |
| Dan Iassogna | 11 | 8 |
| Bill Miller | 10 | 6 |
| Chris Segal | 10 | 7 |
| Doug Eddings | 9 | 5 |
With only a handful of games played, this season could turn into a record-setting year for challenges, especially for veteran umpires who have long been scrutinized for controversial calls.
While pitcher-initiated challenges are still relatively rare, they have appeared early in 2026, even though managers like Alex Cora made it clear before the season that they prefer pitchers not to use the ABS system.
Could challenges become “unlimited”?
Each team is allowed two challenges on balls and strikes. If the umpire’s call is overturned, the team keeps the challenge; if the call stands, they lose one. Given the pace seen on Opening Day, where some games featured multiple successful challenges, it’s fair to expect home plate umpires to face a high volume of reviews throughout the season, adding another layer of pressure to their role.
The first challenge of the 2026 season
The first challenge of the season came from Jose Caballero of the New York Yankees, who disputed a strike call by Bill Miller against the San Francisco Giants, though the call was not overturned. The first successful challenge belonged to Francisco Alvarez on March 26, one day after the first ever challenge. This time, the call was reversed, overturning a ball call in his favor.
