Seattle Mariners at Boston Red Sox: Final Score & Recap

The Seattle Mariners handed the Boston Red Sox a 9-6 defeat at Fenway Park on September 1, 2026, in a game that turned decisively in the second inning. The DiamondIQ model entered the night giving Boston a 61% chance of winning at home, but that number collapsed quickly as Seattle erupted for five runs in the top of the second against Jedixson Paez. Randy Arozarena's home run off Paez carried a +9.1% swing in win probability, and Brock Rodden's single earlier in the inning added another +5.3%. On the other side of the ledger, Trevor Story's pop out to end the bottom of the second represented the single costliest moment of the game for Boston, a -14.0% win-probability swing that effectively sealed the inning's damage and left the Red Sox in a hole they never escaped.

Bryan Woo was the central force in Seattle's victory, contributing +20.1% in win probability added on the pitching side, the most of any player on either roster. Julio Rodríguez led all batters with a +12.7% WPA, highlighted by a strikeout in the top of the second that, from a lineup-sequencing standpoint, carried a +12.0% swing as Seattle maintained its threat against Paez. Arozarena finished with +8.1% WPA and a +0.6 RE24, the only top performer on either side to finish in positive run-expectancy territory. Boston made a brief push in the seventh and ninth innings, but Andrés Muñoz retired Isiah Kiner-Falefa on a groundout to close the ninth, a play that added +6.3% to Seattle's win probability and ended any remaining hope for the home side. The final score of 9-6 was the result of a game Boston never controlled after that pivotal second inning.