Major League Baseball sealed its 2026 rulebook on Thursday, setting the stage for the season’s first ABS challenge system. The new framework will take effect on Opening Day, giving teams a fresh way to contest ball‑strike calls. With the league’s media day in the Cactus Valley, owners confirmed the final guidelines ahead of spring training.

Under the revised rules, a team that enters extra innings without a challenge receives one per inning. Challenges do not stack if unused, and a team cannot hold more than one per frame unless it entered the extra period with both original challenges intact. This tweak keeps the pace tight in late‑game scenarios.

Owners also tightened the obstruction rule, declaring that a runner who deliberately contacts a fielder to force an obstruction call will be called out. Umpires now ignore such stunts, focusing instead on the play’s outcome. Additionally, a new mandate requires base coaches to stay in their boxes until a pitch is released, reducing on‑field interference.

These adjustments aim to sharpen competitive balance and protect player safety. By ensuring teams have a fair chance to challenge in clutch moments and curbing deceptive tactics, MLB signals its commitment to a cleaner, faster game. Fans can expect more decisive calls and a clearer, more consistent flow from the first pitch of the season.