San Francisco Giants at Arizona Diamondbacks: Final Score & Recap

The Arizona Diamondbacks walked off the San Francisco Giants 5-3 on May 19, 2026, at Chase Field in a game that was defined almost entirely by a single swing in the bottom of the ninth. San Francisco held a 3-1 lead through eight innings, but Ketel Marte's walk-off home run off Matt Gage in the bottom of the ninth shifted win probability by +82.1 percentage points, erasing what had appeared to be a comfortable Giants advantage and delivering Arizona a stunning comeback. The DiamondIQ model's estimate opened the night at 64 percent in favor of the home team but spent most of the game's middle innings telling a different story before resetting to 100 percent at the final out.

The path to that decisive moment was paved by missed opportunities and productive Giants pitching. Arizona repeatedly squandered chances to mount earlier pressure, most notably in the bottom of the eighth when Nolan Arenado grounded into a double play off Caleb Kilian, a play that cost the Diamondbacks 35.4 percentage points of win probability. Adrian Del Castillo compounded Arizona's struggles with a grounded-into-double-play against Keaton Winn in the seventh (-26.7% WP) and a strikeout double play off Landen Roupp in the second (-12.6% WP). Those three plays collectively kept San Francisco in control deep into the game. Geraldo Perdomo's walk off Erik Miller in the eighth (+12.1% WP) kept the inning alive and set the table for the eventual Marte at-bat, but it was the home run that rendered everything else secondary.

Marte finished as the game's most impactful performer by a wide margin, posting a +68.4 WPA and +1.7 RE24 on the strength of his decisive blast. Ildemaro Vargas (+15.5% WP) and Ryan Waldschmidt (+11.3% WP) contributed positively for Arizona as well. On the pitching side, the Giants' relievers actually authored a solid collective effort before the ninth unraveled — Keaton Winn led all pitchers at +29.6% WP, followed by Caleb Kilian at +26.6% and Landen Roupp at +16.6% — yet none of it held once Marte connected. San Francisco finished with two errors against Arizona's clean fielding, a detail that factored into the Giants' inability to fully capitalize on their late-game position.