Diamondbacks vs Astros Prediction, Odds, Moneyline, Spread & Over/Under for July 21

Odds updated as of 9:12 p.m.

The Arizona Diamondbacks are among the MLB teams in action on Monday, up against the Houston Astros.

Before you do any MLB betting on this matchup at FanDuel Sportsbook, here's everything you need to know.

Diamondbacks vs Astros Game Info

• Arizona Diamondbacks (50-50) vs. Houston Astros (57-42)
• Date: Monday, July 21, 2025
• Time: 9:40 p.m. ET
• Venue: Chase Field -- Phoenix, Arizona
• Coverage: ARID and SCHN

Diamondbacks vs Astros Odds & Moneyline

• All MLB odds, betting lines and prop bets are available on FanDuel Sportsbook.
• Moneyline: ARI: (-142) | HOU: (+120)
• Spread: ARI: -1.5 (+136) | HOU: +1.5 (-164)
• Total: 9 -- Over: (-108) | Under: (-112)

Diamondbacks vs Astros Probable Starting Pitchers

Probable Pitchers: Zac Gallen (Diamondbacks) - 7-10, 5.40 ERA vs Colton Gordon (Astros) - 3-2, 4.67 ERA

The probable starters are Zac Gallen (7-10) for the Diamondbacks and Colton Gordon (3-2) for the Astros. When Gallen starts, his team is 8-12-0 against the spread this season. When Gallen starts a game and his team is the favorite on the moneyline, they have a record of 5-7. The Astros have a 5-5-0 record against the spread in Gordon's starts. The Astros won each of Gordon's four starts this season that they were the moneyline underdog.

Diamondbacks vs Astros Prediction & Pick

All MLB win probability predictions and picks are according to numberFire.
Prediction: Diamondbacks win (50.7%)

Diamondbacks vs Astros Moneyline

• The moneyline numbers for Diamondbacks vs. Astros reveal Arizona as the favorite (-142) and Houston as the underdog (+120) on the road.

Diamondbacks vs Astros Spread

• The Diamondbacks are favored by 1.5 runs at home against the Astros. The Diamondbacks are +136 to cover the spread, while the Astros are -164.

Diamondbacks vs Astros Over/Under

• Diamondbacks versus Astros, on July 21, has an over/under of 9, with the over being -108 and the under -112.

Bet on Arizona Diamondbacks vs. Houston Astros on FanDuel today!

Diamondbacks vs Astros Betting Trends

• The Diamondbacks have won in 32, or 50.8%, of the 63 contests they have been named as odds-on favorites in this year.
• This year Arizona has won 17 of 31 games when listed as at least -142 on the moneyline.
• The Diamondbacks and their opponents have gone over the total this season in 52 of their 97 opportunities.
• The Diamondbacks have posted a record of 47-50-0 against the spread this season.
• The Astros have an 18-12 record in games they were listed as the moneyline underdog (winning 60% of those games).
• Houston has a 7-1 record (winning 87.5% of its games) when it has played as a moneyline underdog of +120 or longer.
• The Astros have played in 98 games with a set over/under, and have combined with their opponents to go over the total 42 times (42-54-2).
• The Astros have covered 51% of their games this season, going 50-48-0 against the spread.

Diamondbacks Player Leaders

• Geraldo Perdomo leads Arizona OPS (.793) this season. He has a .272 batting average, an on-base percentage of .373, and a slugging percentage of .420.
• He is 54th in batting average, 17th in on-base percentage, and 85th in slugging among all qualifying hitters in baseball.
• Perdomo will look for his fourth straight game with a hit in this contest. In his last five games he is batting .333 with a triple, three walks and seven RBIs.
• Eugenio Suarez leads Arizona in total hits (92) this season while batting .257 with 53 extra-base hits. He's slugging .601 with an on-base percentage of .328.
• Among qualifying hitters, his batting average places him 84th, his on-base percentage 77th, and his slugging percentage fourth.
• Suarez has picked up at least one hit in five straight games. In his last five games he is hitting .500 with a double, six home runs, four walks and 10 RBIs.
• Josh Naylor is batting .292 with a .452 slugging percentage and 58 RBI this year.
• Corbin Carroll has been key for Arizona with 84 hits, an OBP of .328 plus a slugging percentage of .564.
• Carroll has safely hit in two straight games. In his last five games he is hitting .261 with two doubles, three triples, a walk and an RBI.

Astros Player Leaders

• Jose Altuve has a .465 slugging percentage, which paces the Astros. He's batting .278 with an on-base percentage of .338.
• Including all qualified hitters in the big leagues, he is 43rd in batting average, 62nd in on-base percentage and 47th in slugging percentage.
• Yainer Diaz has 11 doubles, a triple, 13 home runs and 14 walks while batting .239. He's slugging .394 with an on-base percentage of .271.
• His batting average ranks 121st among all qualified players, his on-base percentage is 154th, and he is 110th in slugging.
• Cam Smith has 17 doubles, two triples, seven home runs and 27 walks while batting .270.
• Christian Walker is batting .227 with 12 doubles, a triple, 13 home runs and 25 walks.

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