The Arizona Diamondbacks host the Houston Astros on July 21, 2025. First pitch from Chase Field is scheduled for 9:40 p.m. ET; the game will be broadcast on ARID.
Find my MLB betting preview and Astros vs Diamondbacks prediction below, as well as probable pitchers, betting trends, injury reports and more.
My Astros vs Diamondbacks Prediction
- Astros vs Diamondbacks pick: Astros ML +120 or Better
My Astros vs Diamondbacks best bet is Astros moneyline. Make sure to find the best odds by checking our live MLB odds page.
Astros vs Diamondbacks Odds
| Astros Odds | ||
|---|---|---|
| Spread | Total | Moneyline |
+1.5 +142 | 9 -103o / -118u | +119 |
| Diamondbacks Odds | ||
|---|---|---|
| Spread | Total | Moneyline |
-1.5 -172 | 9 -103o / -118u | -141 |
Astros vs Diamondbacks Projected Starting Pitchers
| Colton Gordon (HOU) | Stat | Zac Gallen (ARI) |
|---|---|---|
| 3-2 | W-L | 7-10 |
| 0.5 | fWAR (FanGraphs) | 0.0 |
| 4.67 / 4.01 | ERA /xERA | 5.40 / 4.87 |
| 4.48 / 3.84 | FIP / xFIP | 4.80 / 4.12 |
| 1.42 | WHIP | 1.37 |
| 15.4 | K-BB% | 13.1 |
| 37.8 | GB% | 41.4 |
| 97 | Stuff+ | 90 |
| 110 | Location+ | 104 |
Sean Zerillo’s Astros vs Diamondbacks Preview
The Astros lost Isaac Paredes over the weekend to a hamstring strain, adding to their litany of woes on the injury front. They're supposedly getting Jeremy Pena back pretty soon, but their best hitters are all on the shelf right now.
Paredes was basically the last guy they could afford to lose offensively, and now he's out. Yordan Alvarez has obviously been out for much of the season, too.
They're facing the Diamondbacks tonight, and Arizona is hanging on the fringes of the wild card race right now. Everyone waits and wonders if they're going to sell at the trade deadline.
One of the reasons for the Diamondbacks' struggles is the mediocrity of Zac Gallen, who takes the mound tonight against Houston youngster Colton Gordon.
So, which squad am I backing?
Astros vs Diamondbacks Prediction, Betting Analysis
The Diamondbacks are looking like they're going to sell because even if they somehow make a miracle second-half run, they still don't have great arms for October.
Even when they made the World Series a couple of years ago, they just kept using the same three bullpen arms over and over again. It was Paul Sewald, Justin Martinez and Ryan Thompson getting the shut down innings.
This year, the Diamondbacks have Corbin Burnes and other starting pitchers on the IL, but their bullpen got absolutely shredded. Martinez, Shelby Miller, A.J. Puk and Ryan Thompson are all on the injured list. Kendall Graveman is back, but he was on there for a substantial portion of the season, too.
So, I see an enormous pitching edge for the Astros in this game.
I do project Colton Gordon as a better pitcher than Zac Gallen, and maybe that's a little bit of a hot take. However, he has the way better underlying indicators. Gallen's numbers are basically all in career-worse territory (4.9 expected ERA, 4.12 expected FIP, 13 % K-BB%, 98 Pitching+).
Gordon's Pitching+ is five points better (103 versus 98), but his ERA is a full run better (3.23 versus 4.23) and his K-BB% is a couple of points better.
Both of these pitchers are left-handed starters, and the Diamondbacks are being forced into their lesser split here. Houston is also in its lesser split, but the Astros are one of the best offenses against righties.
As was said earlier, Paredes went down with a hamstring injury over the weekend, and he seems like he's going to be out for a decent amount of time, too.
But the bullpen differential is too strong. The Diamondbacks are missing a lot of arms, and the Astros' advanced stats are much better. It's basically a bottom-10 bullpen (with all the injuries) going up against an elite pen.
I make Houston about +112 in this matchup, so I like it down to +120 or better.
Pick: Houston ML +120 or Better
Moneyline
I like the Astros on the moneyline at +120 or better.
Run Line (Spread)
I don't have a play on the run line.
Over/Under
I show no value on the total.
