Full article at link, some highlights…
How much time does the review add to the game?
In 288 games with the ABS Challenge System during Spring Training 2025, there were an average of 4.1 challenges per game, and those challenges took an average of 13.8 seconds.
So the average game saw about 57 seconds of added time, effectively “giving back” only a small portion of the 26 minutes that the average game time was reduced from 2022 (the last MLB season without the pitch clock) to 2025.
Does the system lead to more pitches per plate appearance?
No, according to the data from testing. In Triple-A, there were an average of 3.92 pitches per plate appearance before ABS and 3.9 afterward. In MLB Spring Training games, the average was static at 3.92.
Are there any scenarios in which a pitch may not be challenged?
When a position player is pitching, challenges are not permitted.
Also, challenges are not permitted after replay reviews, so as to avoid a complex series of challenges.
If there is potential for a replay review after an ABS challenge, umpires will check to see if either manager wants to initiate a replay review before restarting the pitch clock. (If a challenge and a replay review are requested simultaneously, the ABS challenge will be accepted first.)
Are successful challenges retained?
Yes. A team only loses its challenge if the umpire’s call is confirmed.
Because challenges can be lost, it is incumbent upon the player to be judicious about asking for a challenge (i.e., not “wasting” it in a low-leverage spot so that it is available to his team in a high-leverage spot). So in that sense, the ABS Challenge System adds strategy to the sport.
How long do players have to issue a challenge?
Immediately after the pitch (roughly within two seconds). If there is an ensuing play (such as a checked-swing appeal or a play involving a runner), the challenge may be made at the conclusion of the play.
Can an umpire disallow a challenge?
Yes, if the umpire determines that the players’ decision to challenge was aided by other defenders, runners or the dugout, the request will be denied (with the team retaining its challenge). Same goes if the challenge was not requested in a timely manner.
The video below is an example from a Minor League game of what it looks like when an ump
Who can issue a challenge?
The batter, the pitcher or the catcher can challenge an umpire’s call. No one else – no, not even the manager – may do so.
Challenges must be made immediately after the umpire’s call, without assistance from the dugout or other players.
(Some teams have already indicated that they will forbid their pitchers from challenging, preferring they defer to the catcher’s vantage point.)
How is a challenge issued?
The player taps his cap or helmet to alert the umpire to his desire to challenge the call. Players are also encouraged to verbalize their challenge, to leave nothing to doubt, but the cap/helmet tap represents the official challenge.