San Francisco Giants at Boston Red Sox: Final Score & Recap

The Boston Red Sox defeated the San Francisco Giants 6-4 at Fenway Park on August 21, 2026, in a game that turned decisively in the third inning. The DiamondIQ model entered the night giving Boston a 67% chance of winning at home, and a massive five-run third inning made that projection look conservative almost immediately. The defining moment of the game came when Willson Contreras connected on a home run off Logan Webb in the bottom of the third, a swing that added 29.5% to Boston's win probability and served as the centerpiece of that decisive frame. San Francisco answered with a three-run fourth, headlined by a Drew Gilbert home run off Sonny Gray that added 12.8% in win probability from the Giants' perspective, followed closely by a Rafael Devers home run off the same pitcher that contributed another 10.1%. The Giants also generated some early momentum in the third when Bryce Eldridge singled off Sonny Gray for a 9.5% swing, though Boston's lead proved too substantial to overcome.

After the Giants trimmed the deficit in the fourth, Boston extended its cushion in the sixth when Wilyer Abreu ripped a triple off Trent Harris, a hit worth 13.8% in win probability that effectively pushed the model's estimate back toward Boston's favor. By the time the final out was recorded, the DiamondIQ model placed Boston's win probability at 100%. Contreras finished as the game's top performer by WPA at plus-28.3% with a RE24 of plus-3.0, while Abreu posted plus-18.9% WPA and Devers added plus-11.8%. On the pitching side, Boston's bullpen trio of Reiver Sanmartin, Alec Gamboa, and Erik Miller contributed plus-10.8%, plus-8.1%, and plus-7.2% WPA respectively, holding San Francisco scoreless across the final five innings to secure the two-run victory.