We are reader supported. When you purchase through links on our site, we may earn an affiliate commission. Also, as an Amazon affiliate, we earn from qualifying purchases.
Major League Baseball officials are called umpires, not referees. They enforce the rules, make safe-or-out decisions, call balls and strikes, and manage everything from substitutions to replay reviews.
The 2026 MLB season brings a significant change to their responsibilities: the introduction of the Automated Ball-Strike (ABS) Challenge System.
For the first time in regular-season MLB games, eligible players can challenge certain ball-and-strike calls using automated tracking technology. Home plate umpires still make the initial calls, but the new system provides a way to review selected pitches.
Here is how MLB umpiring works in 2026, including each umpire’s responsibilities, the ABS challenge process, replay reviews, and postseason assignments.
Are MLB Officials Called Referees or Umpires?
In baseball, the correct term is umpire.
Although people sometimes search for “MLB referees,” Major League Baseball does not use that title for its on-field officials.
A standard MLB regular-season game uses four umpires:
- Home plate umpire
- First-base umpire
- Second-base umpire
- Third-base umpire
Each umpire has specific responsibilities, but the crew works together to cover plays across the field.
One member serves as crew chief, coordinating communication and helping manage complicated situations.
What Does Each MLB Umpire Do?
Home Plate Umpire
The home plate umpire stands behind the catcher and has several important responsibilities.
These include:
- Calling balls and strikes
- Monitoring the pitch timer
- Enforcing batter and pitcher violations
- Calling plays at home plate
- Handling substitutions and lineup matters
- Coordinating with other umpires on disputed calls
In 2026, the plate umpire also plays an important role in the ABS challenge process.
The umpire continues to call each pitch in real time. If an eligible player challenges the call, the automated system determines whether the pitch crossed the designated strike zone.
The plate umpire then applies the resulting decision.
First-Base Umpire
The first-base umpire primarily handles plays around first base.
Responsibilities include:
- Safe and out calls
- Force plays and tag plays
- Pickoff attempts
- Fair-or-foul decisions near first base
- Certain checked-swing appeals
When a right-handed batter attempts to stop a swing, the plate umpire may ask the first-base umpire for assistance.
Positioning is especially important because many first-base calls involve a close race between the runner and the throw.
Second-Base Umpire
The second-base umpire handles many plays involving the middle infield.
These include stolen-base attempts, double plays, force plays, and tags at second base.
This umpire also helps identify interference and obstruction.
Because plays at second base often involve sliding runners and moving fielders, the umpire must establish a clear angle to see whether a tag was applied before the runner reached the base.
Third-Base Umpire
The third-base umpire covers plays around third base and assists with fair-or-foul decisions along the third-base line.
Other responsibilities include:
- Tag plays at third base
- Force plays
- Pickoff attempts
- Checked-swing appeals involving left-handed batters
- Outfield coverage according to crew positioning
Like the other base umpires, the third-base umpire adjusts positioning depending on runners, outs, and the location of the ball.
Crew Chief
The crew chief is the designated leader of the umpiring crew.
This umpire helps coordinate unusual rules situations, communicates with managers, and manages disagreements when necessary.
The crew chief also plays an important role in replay procedures and communication with MLB’s Replay Operations Center.
However, the crew chief does not personally make every decision. Individual umpires remain responsible for calls within their assigned coverage.
How the ABS Challenge System Works in 2026
The biggest umpiring development for the 2026 MLB season is the Automated Ball-Strike Challenge System.
Unlike a fully automated strike zone, the challenge system preserves the home plate umpire’s role in calling pitches.
The technology is used only when an eligible player challenges a specific ball-or-strike decision.
Who Can Challenge a Pitch?
Under the ABS challenge format, challenges can be initiated by:
- The batter
- The pitcher
- The catcher
Managers and other players cannot initiate a challenge on their behalf.
The challenge must be made immediately after the pitch, before the next play begins.
How Many ABS Challenges Does Each Team Get?
Each team begins a regulation game with two ABS challenges.
A successful challenge is retained.
An unsuccessful challenge is lost.
This means teams must decide when a disputed pitch is important enough to challenge.
Additional provisions apply in extra innings.
What Happens During an ABS Challenge?
The process is straightforward.
- The plate umpire makes the initial ball-or-strike call.
- An eligible player immediately signals a challenge.
- The automated tracking system evaluates the pitch.
- The result is displayed to the stadium and broadcast audience.
- The original call is either upheld or overturned.
The system is designed to resolve challenges quickly without requiring a traditional video replay review.
Does ABS Replace Home Plate Umpires?
No.
The plate umpire still calls balls and strikes throughout the game.
ABS does not automatically evaluate every pitch for the purpose of replacing the umpire’s call.
Instead, it provides a limited challenge mechanism.
Home plate umpires also continue to enforce the pitch timer, manage substitutions, make calls at home plate, and handle other rules situations.
The distinction matters: MLB uses an automated challenge system, not a fully automated home plate umpire.
MLB Instant Replay Rules in 2026
ABS challenges and traditional instant replay are separate systems.
ABS addresses eligible ball-and-strike challenges.
Traditional replay covers specified on-field rulings, such as certain safe-or-out decisions and boundary calls.
How Traditional Replay Works
When a manager challenges a reviewable ruling, the on-field crew communicates with MLB’s Replay Operations Center in New York.
Replay officials examine the available video and determine whether the original ruling should remain in place.
Possible outcomes include:
Confirmed: The available evidence supports the original call.
Stands: There is insufficient evidence to change the original ruling.
Overturned: The evidence supports changing the ruling.
The result is communicated to the on-field crew and announced to the stadium.
Which Plays Can Be Reviewed?
Depending on the applicable replay rules, reviewable situations include:
- Certain safe-or-out calls at bases
- Home run and boundary decisions
- Fair-or-foul rulings on eligible balls
- Catch-or-no-catch decisions
- Certain hit-by-pitch situations
- Selected runner placement and scoring questions
Not every disputed call is reviewable.
For example, checked-swing judgments generally remain outside traditional replay review.
Ordinary ball-and-strike calls are handled through the separate ABS challenge process.
How MLB Umpire Crews Rotate
A standard regular-season MLB umpiring crew consists of four officials.
Crew members generally rotate among home plate and the three bases during a series.
This rotation distributes plate assignments and gives each umpire experience at different positions.
The exact assignment schedule can change because of injuries, substitutions, and operational needs.
If an umpire becomes unavailable, MLB may assign another official to fill the vacancy.
Some replacement umpires are experienced Triple-A officials who receive temporary major-league assignments.
How Many Umpires Work MLB Playoff Games?
MLB postseason games typically use six on-field umpires rather than four.
The additional officials provide coverage along the left-field and right-field lines.
This expanded crew helps with boundary decisions, fly balls, and other plays that can be difficult to judge from the infield.
Postseason assignments are made by MLB and may include experienced umpires serving as crew chiefs.
What Other Rules Do MLB Umpires Enforce?
Pitch Timer Violations
MLB uses a pitch timer to regulate the pace of play.
Pitchers must begin their delivery before the applicable timer expires.
Batters must also be ready within the required time.
Violations can result in an automatic ball or strike, depending on which player commits the violation.
Pitcher Disengagement Limits
Pitchers are subject to limits on disengagements from the pitching rubber during a plate appearance when runners are on base.
Disengagements include certain pickoff attempts and step-offs.
An additional disengagement beyond the permitted limit can result in a balk if the attempt does not retire a runner.
Umpires track these actions and enforce the rule.
Obstruction and Interference
Obstruction generally involves a defensive player illegally hindering a runner.
Interference can involve an offensive player illegally hindering a defensive play.
These rulings require umpires to evaluate the players’ actions and apply the relevant rule.
Not every collision or instance of contact automatically constitutes a violation.
Home Plate Collisions
MLB has specific rules governing collisions at home plate.
Catchers generally cannot block a runner’s path without possession of the ball unless the applicable rules permit their positioning while fielding a throw.
Runners also face restrictions on avoidable collisions.
Umpires evaluate these situations based on the circumstances of the play.
Foreign Substance Checks
Umpires enforce MLB’s restrictions on prohibited foreign substances.
Pitchers may be inspected during games, and violations can result in ejections and additional league discipline.
These inspections are separate from ordinary equipment checks.
How Do You Become an MLB Umpire?
Reaching Major League Baseball usually requires years of professional training and experience.
Candidates generally begin through professional umpire development programs and work their way through minor-league assignments.
Advancement depends on factors such as:
- Rules knowledge
- Accuracy and consistency
- Positioning and mechanics
- Communication
- Game management
- Professional evaluations
Some minor-league umpires receive temporary MLB assignments before earning permanent positions. MLB umpire salaries vary depending on experience and employment status.
The process is competitive, and there is no guaranteed timeline for reaching the major leagues.
What Should Fans Watch During the 2026 Season?
Three developments are especially relevant.
1. ABS Challenge Decisions
The introduction of ABS creates a new strategic element.
Players must decide whether to challenge a borderline pitch, particularly in situations where the count could significantly affect an at-bat.
Fans can also compare the umpire’s original call with the automated result.
2. How Umpires Manage Replay and ABS
Traditional replay and ABS challenges serve different purposes.
Watching how crews communicate these decisions can help fans understand which calls are eligible for review and why some rulings cannot be challenged.
3. Postseason Umpire Assignments
The postseason brings expanded umpiring crews and greater scrutiny of close decisions.
Fans can observe how additional outfield-line umpires improve coverage and how crew chiefs manage high-pressure situations.
Frequently Asked Questions
Are MLB referees called umpires?
Yes. The correct term for Major League Baseball officials is umpires. The word referee is commonly used in other sports.
How many umpires are in an MLB game?
A standard regular-season MLB game has four on-field umpires. Postseason games typically use six.
Does MLB use robot umpires in 2026?
MLB introduced the ABS Challenge System for the 2026 season. Human plate umpires continue calling pitches, while eligible players can challenge certain decisions using automated technology.
Can managers challenge balls and strikes?
Managers cannot initiate ABS challenges. Eligible challenges must come from the batter, pitcher, or catcher.
Are all MLB umpire calls reviewable?
No. Traditional instant replay covers specified types of rulings. ABS challenges apply separately to eligible ball-and-strike decisions.
Do MLB umpires rotate positions?
Yes. Regular-season umpiring crews generally rotate assignments among home plate and the three bases.
Conclusion
MLB umpires do much more than call balls and strikes.
They manage the game, enforce rules, judge close plays, coordinate replay reviews, and communicate decisions to players and managers.
The introduction of the ABS Challenge System in 2026 adds an important new responsibility without eliminating human plate umpires.
Understanding how the four-person crew works, how replay differs from ABS, and which calls remain judgment decisions makes it easier to follow the game.
For fans searching for information about MLB referees in 2026, the essential point is simple: baseball still relies on umpires, but technology now plays a larger role in reviewing selected decisions.