Giants vs Diamondbacks Picks and Prediction – 7/2/2025

The San Francisco Giants (45–39) hit the road to take on the scrappy Arizona Diamondbacks (41–42) in a midweek showdown that could shift playoff momentum. The D-backs call on ace Zac Gallen (5–9, 5.75 ERA) to right the ship, while the Giants turn to rookie Hayden Birdsong (3–2, 4.13 ERA), making another spot start after bouncing between rotation and bullpen. Expect fireworks—or shutdowns—under the (indoor) desert sky. Get in on the action with our free MLB picks.

For the Arizona DIamondbacks, Gallen‘s season has been a roller coaster: his 5.75 ERA ranks among the worst of qualified starters, but he has shown flashes—last summer he struck out 11 Giants across six scoreless innings . Entering tonight, the Diamondbacks are limping at 1–4 in their last 5 SU and ATS, yet have dominated previous home series vs. San Francisco—winning 8 of the last 11. Their bats, however, have cooled, though Chase Field remains a run-friendly park.

On the side of the San Francisco Giants, Birdsong continues to grow in his MLB role. Since moving to the rotation, he’s posted a 4.13 ERA in five starts but was hit hard in his last outing (five runs in 3⅔ innings vs. the Brewers). Still, he’s capable—opponents bat just .217 off him overall . The Giants are 5–1 ATS in their last 6 games vs. Arizona, and the acquisition of Rafael Devers adds middle-of-order pop.

Gallen has had a shaky season, there is no doubt about it. But with San Francisco’s recent slide, we are willing to back Gallen to show a little of what made him so great a season ago. We like the Diamondbacks on the moneyline, but know this will be a closely contested game. We will be backing Arizona to win a fun one, by a score of 5-4.