MLB's ABS: Early Challenges & Lessons Learned

Baseball has entered a new era with the automated ball-strike (ABS) system, and some players are adapting more quickly than others. MLB’s new challenge system for balls and strikes has been active for only a few days, fundamentally altering baseball strategy.

The Strategic Shift of ABS Challenges

Players have always questioned umpire calls; now, they can challenge them. However, teams have only two unsuccessful challenges per game, making strategic decision-making crucial. Choosing the right moment to challenge is as important as being correct about the call itself.

Best ABS Challenges of Opening Week

Helsley's Game-Saving Challenge

With the Orioles leading the Twins 8–6 in the top of the ninth, Twins pitcher Griffin Jax faced Josh Bell with a full count. A pitch that initially was called a ball was challenged by Jax and overturned. This challenge resulted in a 13.3% Win Probability Added (WPA), the most impactful challenge of the young season.

Suárez's Double Challenge

Facing the Red Sox with the bases loaded and two outs in the bottom of the sixth, Yandy Díaz received back-to-back strike calls and successfully challenged both. The resulting crowd reaction added a new dynamic to the game, demonstrating the potential for fan engagement with the system.

Worst ABS Challenges of Opening Week

Wallner's Costly Miss

In the same Twins-Orioles game, with the bases loaded and two outs in a tie game, Matt Wallner challenged a strike three call. The challenge was unsuccessful and used Minnesota’s final challenge for the game. The pitch was 4.77 inches from the edge of the strike zone, the furthest distance of any challenged pitch this year.

Pomeranz & O'Hoppe's Oversight

Angels pitcher Drew Pomeranz appeared to catch the strike zone on a 2–2 pitch to Isaac Paredes. Neither Pomeranz nor catcher Logan O’Hoppe challenged the call, and Paredes doubled on the next pitch, costing the Angels 10.5% WPA.

Nuñez's Ill-Timed Challenge

Nationals batter Eddie Nuñez challenged a 1–1 pitch with the bases loaded, leading 3–2. The failed challenge left the team with no remaining challenges, and Nuñez struck out later in the at-bat.

Acuña's Early Gamble

Ronald Acuña Jr. challenged a 1–0 count against the Royals, resulting in a failed challenge and a loss of 1.3% WPA. This highlighted that the cost of losing a challenge can outweigh the benefit of a potentially overturned call.

Early Lessons from the ABS System

The initial days of ABS have shown that the decision to challenge is often more important than the outcome of the challenge itself. Too many players have challenged calls early in games, wasting valuable resources. Prior to Tuesday’s games, 11 overturned challenges in the first inning had no meaningful impact on the game’s outcome.

Adjustments to significant rule changes take time. However, players would be wise to reserve challenges for later in the game—or at least after the first inning.

Nick Selbe is a programming editor at Sports Illustrated who frequently writes about baseball.