Chicago Cubs at Arizona Diamondbacks: Final Score & Recap

Arizona walked off Chicago 5-4 at Chase Field on August 25, 2026, in a game that was decided by a single swing in the bottom of the ninth. The DiamondIQ model opened the night with the Diamondbacks holding a 49 percent home win probability, a figure that barely moved through seven innings before the game's final two frames rewrote the outcome entirely.

The Cubs appeared to seize control in the top of the fourth, when Ian Happ launched a home run off Brandon Pfaadt that shifted win probability by 19.7 percent in Chicago's favor, and Michael Busch added a double moments later for another 11.1 percent swing, helping the Cubs plate three runs in the inning and carry a 3-0 lead into the middle innings. A solo shot in the sixth pushed the Cubs' advantage to 4-0. Arizona responded in the bottom of the eighth, where Geraldo Perdomo's single off Daniel Palencia moved the needle 22.9 percent toward the home side as the Diamondbacks scored three to cut the deficit to one. Max Kepler's groundout against Jacob Webb in that same frame cost Arizona 12.9 percent in win probability, leaving the team still trailing heading to the ninth.

That deficit lasted exactly until Ryan Waldschmidt stepped in against Jacob Webb with the game on the line. His walk-off home run produced the single largest win-probability swing of the night at plus-90.2 percent, carrying the DiamondIQ model's estimate from a precarious position all the way to a final reading of 100 percent. Waldschmidt finished as the game's top performer by both WPA and RE24 at plus-90.2 and plus-1.9 respectively, with Perdomo close behind at plus-24.5 WPA and plus-1.9 RE24. On the pitching side, Clay Holmes was the top performer by WPA at plus-28.2 percent for Arizona.