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Rockies vs Diamondbacks Prediction: Gallen Looks to Build Momentum in Series Opener
The Arizona Diamondbacks return home to Chase Field on Friday, August 8, 2025, to open a three-game set against the Colorado Rockies. First pitch is scheduled for 9:40 PM ET, with Zac Gallen toeing the rubber for Arizona opposite lefty Austin Gomber for Colorado.
The Diamondbacks (54-61) are favored at -238 on the moneyline after dropping their last two games. The Rockies (30-84) limp in after being swept by Toronto in historic fashion, giving up 45 runs over three games.
More Wins. More Confidence.
No guesswork, just guidance
Rockies Can Win If…
They put their Coors Field disaster in the rearview mirror and get a quality start from Austin Gomber. The lefty (0-5, 6.18 ERA) was roughed up for nine runs in 4 2/3 innings the last time he faced Arizona, so avoiding early trouble will be key.
Offensively, Colorado needs production from Ezequiel Tovar, who is 6-for-10 with a homer in his career against Gallen. The Rockies have hit 186 doubles this season (11th in MLB), and finding the gaps will be critical to manufacturing runs against Arizona’s ace.
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Diamondbacks Can Win If…
Zac Gallen (8-12, 5.48 ERA) continues trending upward. He’s posted three quality starts in his last six outings and limited Oakland to two runs over six innings in his last appearance. Historically, Gallen has dominated Colorado, going 8-1 with a 3.53 ERA in 17 career starts.
Arizona’s offense remains a strength, ranking 4th in slugging percentage (.436) and 6th in both home runs (158) and doubles (198). With Ketel Marte (10-for-26, 3 HR vs Gomber) and Corbin Carroll providing punch, the Diamondbacks have the tools to get to Gomber early and hand the ball to their bullpen with a lead.
Key MLB Betting Trends
| Trend Type | Rockies | Diamondbacks |
|---|---|---|
| Moneyline Form | Lost 4 straight | Lost 2 straight |
| Run Line Record | 1-6 in last 7 games | Covered 4 of last 6 wins |
| Total (O/U) | Over is 6-3 in last 9 road games | Over is 4-1 in last 5 home games |
| Head-to-Head | Lost 5 of last 7 vs Arizona | Won 5 of last 7 vs Colorado |
The Lean
The Rockies’ pitching woes — they own MLB’s worst ERA at 6.04 — combined with Gallen’s history of success against them point to Arizona. My model projects the Diamondbacks to win 6-4.
Best Bet: Diamondbacks ML (-238)
Bonus Lean: Over 9.0 (-109) — both lineups have the extra-base power to take advantage of shaky pitching.
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