Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsMLB replay review can change only calls in specified reviewable categories; the Automated Ball-Strike (ABS) Challenge System can change only a home-plate umpire’s called ball or strike. In 2026, the umpire still makes the initial pitch call. ABS is a player-initiated challenge process, not automatic calling of every pitch.
At a glance: the two systems have different jobs
| Question | Replay review | ABS Challenge System |
|---|---|---|
| What can be reviewed? | Calls in MLB’s enumerated reviewable categories. | A home-plate umpire’s called ball or strike. |
| Who starts the review? | A manager challenges, or the crew chief initiates review when authorized. | The batter, pitcher or catcher involved immediately taps a cap or helmet. |
| Who or what decides? | MLB replay officials at the Replay Command Center review the play. | Hawk-Eye pitch tracking checks the pitch against the ABS zone; the result is relayed and displayed. |
| What can change? | An eligible play call and, when needed, runner placement to reconstruct the proper result. | The ball-or-strike call. Other play outcomes are adjusted only when affected by that call. |
| How is a change decided? | There must be clear and convincing evidence to change the call; otherwise it is confirmed or allowed to stand. | The tracked location is compared with the defined strike zone. |
These are separate procedures, not two names for the same review. MLB’s replay-review rules define the eligible play categories, while its ABS rules and explainer describe a narrow appeal of a pitch call.
What MLB replay review can change
MLB limits replay review to listed categories; it does not cover every close call. A manager challenge or an authorized crew-chief review sends the call to full-time MLB umpires at the Replay Command Center. They can change, confirm or let the call stand. The glossary says officials are expected to decide within two minutes, with exceptions, and that a replay decision is final.
Home runs, boundaries and fair or foul calls
- Potential home-run questions, including whether a ball left the field, hit a fence or object, involved fan interference, or was fair or foul.
- Specified non-home-run boundary calls, such as a live ball bouncing out, hitting an obstacle, being caught near a boundary, or becoming dead after leaving the field.
- Some fair-or-foul calls: review is limited to balls first landing at or beyond the first- or third-base umpire’s set position.
Force plays, tags, catches and baserunning
- Force and tag plays, including whether a fielder touched a base or tagged a runner and whether the runner acquired the base.
- Outfield catch-or-no-catch calls on fly balls or line drives; infield catches are not reviewable under this category.
- Specified baserunning decisions, including whether a runner passed a preceding runner, scored before a third out or touched a base.
- Certain tag-up calls, collisions at home plate, runner placement after a boundary call and interference on double plays.
Hit-by-pitch calls—and an important exclusion
Replay can review whether a pitched ball hit a batter, the batter’s clothing or the bat. It cannot review whether the pitch was in the strike zone when it touched the batter, or whether the batter tried to avoid being hit. Those are distinct judgments, not a general invitation to review the pitch’s ball-or-strike status.
Recommended Free Tools
#1 Best Overall
What the ABS Challenge System can change
Under MLB’s 2026 system, only the batter, pitcher or catcher involved may challenge the plate umpire’s initial ball-or-strike call. The player must signal immediately with a cap or helmet tap. Coaches, teammates and the dugout cannot request or assist with the challenge.
Each team begins with two challenges and retains a challenge when successful. A team entering an extra inning with none receives one for that inning. MLB’s 2026 ABS explainer also lists situations in which a challenge is barred.
How the ABS strike zone is measured
MLB defines the ABS zone as a two-dimensional rectangle at the midpoint of home plate. It is 17 inches wide, matching the plate. Its upper boundary is 53.5% of the hitter’s measured height and its lower boundary is 27%. If any part of the ball touches any part of that rectangle, the pitch is a strike. MLB says twelve Hawk-Eye cameras track pitches, with results shown to ballpark spectators and broadcast viewers. See MLB’s description of ABS strike-zone geometry.
What the test figures do—and do not—show
In MLB’s 2025 Spring Training test across 288 games, there were 4.1 challenges per game, and each challenge took an average of 13.8 seconds. MLB reported that 52.2% of challenged calls were overturned and that 2.6% of called pitches were challenged. In the same test, pitchers and catchers succeeded on 54.4% of challenges, compared with 50.0% for hitters. These are Spring Training test results, not guaranteed 2026 regular-season rates. MLB also reported 88,534 tracked pitches in that test, with four unavailable because of tracking glitches.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Rank #3
MLB’s 2026 explainer reports that, in 2-2 counts, the umpire-called zone measured 449 square inches and the ABS zone 443 square inches in MLB research. MLB presents a slight reduction in strikeouts and increase in walks as expectations based on testing, not established 2026 outcomes.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.When ABS challenges and replay review intersect
The procedures have explicit interaction rules, but an ABS challenge does not turn replay review into a ball-or-strike review. MLB says an ABS challenge cannot be made when a position player is pitching or after replay review. If an ABS challenge and replay review are requested at the same time, the ABS challenge is accepted first.
When the challenged pitch occurs during action involving runners, calls unaffected by the mistaken ball-or-strike ruling remain in place; only the affected result is adjusted. MLB gives the example of a runner who remains safe at third after a steal even when a challenged ball becomes strike three and retires the batter. If a dropped pitch is overturned to strike three, the batter is out without the usual tag or force at first.
Replay review’s listed categories do not establish a general way to reverse an ordinary ball-or-strike judgment. The replay glossary expressly excludes the strike-zone status of a pitch that hits a batter.
Best Value
- Baseball field guide an in depth illustrated guide to the complete rules of baseball
- Language: english
- Book - baseball field guide: an in-depth illustrated guide to the complete rules of baseball
How replay review decisions differ from ABS outcomes
Replay officials change a reviewable call only when the evidence is clear and convincing; otherwise the call is confirmed or allowed to stand. ABS instead checks the challenged pitch’s tracked location against a zone whose width is fixed and whose vertical boundaries depend on the hitter’s measured height. The first process reviews a play from a limited menu; the second tests one specific pitch judgment.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
