Chicago Cubs at Seattle Mariners: Final Score & Recap

The Chicago Cubs handed the Seattle Mariners a 7-1 defeat at Peoria Stadium on March 21, 2026, collecting 15 hits while limiting Seattle to just five. The DiamondIQ model entered the game giving the home side a 47% chance of winning, but by the final out that figure had fallen to 0%, a collapse driven almost entirely by a six-inning stretch of Cubs offense that Seattle's pitching staff could not contain.

The decisive sequence arrived in the top of the sixth, when the Cubs broke open what had been a tightly contested game. Ben Cowles delivered a single off Gabe Speier that shifted win probability by +21.4 percentage points, the single largest swing of the contest, and Dylan Carlson followed with a home run off the same pitcher for an additional +14.6-point swing. Together those two at-bats accounted for the bulk of the game's three-run sixth and effectively ended Seattle's realistic path back into the game. The Cubs added three more runs in the top of the eighth to make it a rout, and Seattle's best chance to change the complexion of the game had come and gone in the third inning, when Brendan Donovan's flyout off Colin Rea represented a -7.9-point swing that left a potential Mariners rally on the vine.

Among individual performers, Cowles finished as the game's top batter by the DiamondIQ model's estimate, posting a +18.9% WPA and +1.9 RE24, while Carlson contributed +16.6% WPA and +1.0 RE24. On the mound, George Kirby led all pitchers at +22.1% WPA despite working for the losing side, getting key outs including a double play off Miguel Amaya in the fifth that swung probability -11.3 points against the Cubs. Colin Rea added +8.8% WPA in his stint for Chicago, and Evan Taylor contributed +6.3% WPA, aided by a seventh-inning double play off Ryan Bliss that closed out Seattle's final meaningful threat.