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Arizona Diamondbacks vs. Houston Astros prediction, pick for Monday 7/21/25

Arizona Diamondbacks vs. Houston Astros prediction, pick for Monday 7/21/25

Updated:

By: Keagan Smith

The MLB’s Monday slate wraps up with three games in the late-night window. One of those takes place in the arid desert as the Arizona Diamondbacks welcome the Houston Astros for the first leg of a three-game set.

Here’s a Diamondback vs. Astros prediction and pick on DraftKings Sportsbook for Monday evening’s contest.

Diamondbacks vs. Astros prediction, preview

Injuries have been the story of both these teams’ seasons thus far — how they’ve weathered them feels a bit different between the two. The Diamondbacks have really missed ace pitcher Corbin Burnes along with reliever A.J. Puk and closer Justin Martinez, all threw of whom had their seasons ended prematurely with elbow injuries. First baseman Pavin Smith is on the short-term IL at the moment, while catcher Gabriel Moreno continues healing a fractured finger on the 60-day IL. The Snakes find themselves fourth in the NL West at 50-50 on the campaign as they float near the .500 mark and decide whether to sell or sit tight at the upcoming trade deadline.

Meanwhile, the Astros haven’t seen star slugger Yordan Alvarez take the field since May 2 and are still missing starting pitchers Ronel Blanco, Cristian Javier, Luis Garcia, the latter two of whom continue rehabbing season-enders suffered in 2024. Houston kept winning for a time even in Alvarez’s absence and as the rotation thinned with a couple of minor ailments, but after All-Star Jeremy Pena and centerfielder Jake Meyers hit the IL with their own injuries, things took a turn for the worse. Those issues culminated as another All-Star, Isaac Paredes, landed on IL last night after suffering a hamstring injury. They’re quite banged up and are slumping over their last three series, but Houston remains atop the AL West at 57-42.

It’s no fun to start a write-up with an extensive list of players who won’t take the field, but it’s impossible to cover this game without mentioning how unlucky both franchises have been this season.

As for tonight’s game, the Diamondbacks’ lineup somehow looks much healthier than the Astros’ does. Arizona brings plenty of power hitting to the table and a handful of stars with Ketel Marte, Corbin Carroll, Eugenio Suaraz and Geraldo Perdomo. Houston doesn’t have the same star power with Jose Altuve, Cam Smith, Yanier Diaz and Christian Walker as their four most recognizable names in tonight’s lineup for casual fans. All things considered, the Astros still remain shorthanded especially at the bottom of the order.

Diamondbacks vs. Astros pick, best bet

The Diamondbacks enter this matchup as -144 Moneyline favorites on DraftKings Sportsbook while the Astros come in as +118 underdogs. The run total sits at an even nine.

DraftKings Network just introduced a new probable pitchers page to track daily starter matchups, so be sure to check that out ahead of the game! Tonight, Arizona righty-hander Zac Gallen (5.40 ERA, 1.37 WHIP, 110 SO) faces off against Houston lefty Colton Gordon (4.67 ERA, 1.42 WHIP, 44 SO).

Gordon hasn’t exactly looked great this season and is coming off a nine-hit, four earned run outing on July 1 followed by a seven-hit, five earned run performance on July 7. He did throw one more time after those games but exited after just one inning due to injury. Against a Diamondbacks lineup that has plenty of pop and tallied 22 runs over their first three games following the All-Star break, Gordon and the ‘Stros bullpen face a real challenge tonight. Diamondbacks -1.5 feels pretty good at +138 odds, but I’m targeting over 4.5 runs for Arizona instead just to feel safer since Gallen isn’t having a great year in the earned runs department.

Best bet: ARI Diamondbacks over 5.5 team total runs (+155)

Click the odds on this bet to tail!

Keagan is a Texas-based editor and analyst who believes sports are the true eighth wonder of the world. After starting out in local media, he’s provided coverage for DraftKings Network since 2024. He gravitates toward football, hoops and hockey, but is happy to watch and write about any game that involves a ball or a puck. While his own athletic career ended in middle school, he’s also an avid fantasy player with a soft spot for dynasty formats, spending countless hours crafting the ever-elusive perfect squad.
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