The Mariners’ first run through MLB’s Automated-Ball Strike System was a mixed bag, and the biggest issue showed up right where they could least afford it: at the plate.
Across the 2026 regular season, MLB teams had 54% of their challenges overturned on average, according to Baseball Savant. Seattle landed below that mark at 50.7%, and the numbers get tougher from there once you split the results between offense and defense.
When the Mariners were hitting, the challenges just didn’t go their way often enough. MLB hitters as a whole won 49% of their offensive challenges, but Seattle checked in at 41.7%, going 68 of 163.
That was second worst in the league. It also left the Mariners second worst in challenge overturns vs. expected at minus-23.5, a measure of how many net overturns a team produced compared with what would be expected from the same set of pitches.
Even so, Seattle still found some value on offense from the system. The Mariners were tied for seventh in walks gained on challenges with 12, and they ranked 10th in strikeouts erased with 23.
The biggest drag on those offensive numbers came from two familiar bats. Josh Naylor and Randy Arozarena accounted for nearly one-third of Seattle’s offensive challenges, combining for 54 of the team’s 163.
Naylor struggled the most, posting a 27% success rate, going 7 of 26. Among players with at least 25 challenges, that was third worst in MLB.
Arozarena wasn’t far behind in the wrong direction, finishing at 39% success rate, 11 of 28, which ranked 15th worst.
Cal Raleigh was the clear bright spot for Seattle on the offensive side. He led the club with 14 successful challenges and was the team’s most efficient challenger, minimum five challenges, at 64% (14 of 22).
Raleigh also paced the Mariners in strikeouts erased with seven and walks gained with five, marks that were tied for second and tied for first, respectively, leaguewide. His 4.6 runs gained on offensive challenges were second in baseball, behind Houston’s Jose Altuve.
Seattle was better when it came to challenging pitches while in the field. The Mariners finished at 59.3%, a shade above the league average of 58%, and ranked 13th in MLB.
They also had 37 strikeouts gained, seventh most, and 10 walks erased, tied for the 10th fewest. Overall, Seattle finished with 2.9 more overturns than expected, which also placed them 13th.
Behind the plate, Mitch Garver was the standout before his release in August. He won 25 of 34 challenges for a 74% success rate, third best among MLB catchers who challenged at least 20 pitches.
Raleigh was solid as well while catching, posting a 61% success rate on 54 of 88 challenges. Jhonny Pereda finished at 45% on 19 of 42.
On the mound, George Kirby was the only Mariners pitcher to challenge more than one pitch, and he went 1 for 5. His four unsuccessful challenges were tied for the second most among pitchers across the league. The three other Seattle pitchers who challenged one pitch each were perfect, going 1 for 1.
And as for whether any of this actually tracked with winning, the first year of ABS didn’t offer much proof. The teams that were best at successful offensive challenges did not reliably turn that into postseason trips, and the same was true on defense. Even the top overall teams in total successful overturns were all over the map, while the Dodgers won 100 games and still finished with the sixth-fewest total overturns for.
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