Diamondbacks Have Chance to Continue Turnaround vs Astros

The Arizona Diamondbacks came out of the All-Star Break hot, sweeping the St. Louis Cardinals in a series they simply had to have.

The D-backs improved to 50-50, hoping to stave off a seller's fate at the Trade Deadline.

Meanwhile, the Astros sit atop the AL West at 57-42, four games ahead of the Seattle Mariners. They have lost seven of their last 10 games, however, dropping two of three to the Mariners out of the break.

Arizona Diamondbacks vs Houston Astros Pitching Matchups

Monday, July 21: RHP Zac Gallen (5.40 ERA) vs LHP Colton Gordon (4.67 ERA)

The former D-backs ace appeared to have turned a corner recently with back-to-back gems, but that did not carry over into his most recent Angel Stadium start. Gallen gave up six runs on eight hits over just five innings against Los Angeles.

He's had success in his career against the Astros, with a 3.16 ERA in five starts, although he hasn't faced Houston since 2023.

Gallen was given an extra day's rest before his two recent dominant starts, however, so the long break could allow him to come out sharper. Arizona needs it.

Astros Left-hander Colton Gordon has had mixed results in his first 10 career starts. He pitched to a 2.14 ERA in June, but struggled in July, giving up nine earned runs in his first 10.1 innings of the month, seeing his ERA balloon to 4.67.

He most recently made a scoreless one-inning relief appearance on July 13, but has been named the starter for Monday's game.

Tuesday, July 22: LHP Eduardo Rodriguez (5.94 ERA) vs LHP Framber Valdez (2.75 ERA)

Similarly to Gallen, left-hander Eduardo Rodriguez showed flashes of a turnaround before falling back down to earth. After pitching to a 1.98 ERA in the month of June, Rodriguez has been knocked around for 13 runs in his last 8.1 innings.

Houston has slugged left-handers nearly 70 points higher than righties in 2025, offering a potential dangerous matchup for Rodriguez.

Ace southpaw Framber Valdez has been excellent in the 2025 season. Save for a few rough outings, he's been his usual dominant self, pitching to a 2.75 ERA over 121 innings.

Most recently, Valdez punched out 10 over six innings, giving up just one unearned run against the Rangers. He's collecting strikeouts and ground balls at a high rate, and has given up just eight homers in 19 starts.

Wednesday, July 23: RHP Brandon Pfaadt (4.82 ERA) vs TBA

Brandon Pfaadt, after struggling for some time, has delivered back-to-back excellent starts for the D-backs.

He went a career-high eight innings with just two runs against the Padres on July 9, then tossed seven scoreless innings against the Cardinals his next time out, dropping his ERA below 5.00 for the first time since late May.

Pfaadt is one of just three National League pitchers with 10 wins. While that isn't a stat that carries much weight in today's game, Arizona has had great success when Pfaadt delivers a quality outing.

The Astros have not announced their starter for Wednesday as of this writing. Left-hander Brandon Walter pitched on July 18, and lines up in this slot however. He's 1-3 with a 3.66 ERA

Diamondbacks vs Astros Offenses

Houston ranks dead center of MLB in runs scored at 15th, although they're 12th in OPS (.732) and 13th in home runs (112).

Three of their best hitters will miss the series however. Jeremy Peña still leads the Astros in OPS (.867), but he's been down on the IL with a fractured rib since June 30.

Isaac Paredes leads the club in homers with 19, but just went down with a hamstring injury and was placed on the 10-day IL.

Yordon Alvarez has been on the IL since May 3 with a fractured hand. He's nearing return, but likely not back before the weekend.

Ever present Jose Altuve is slashing a sturdy .278/.338/.465 with 17 homers.

Former Diamondbacks first baseman Christian Walker has struggled this season. He's hitting just .230 with 13 homers, good for a .669 OPS, and has struck out 107 times against 25 walks. He struck out 133 times in all of 2024 with Arizona.

The D-backs' offense was explosive in their recent sweep, and remains one of the more daunting groups in MLB. They rank fourth in runs scored (515), fifth in home runs (145) and second in OPS (.777).

Corbin Carroll has tripled three times in his last two games, and Eugenio Suárez continues to lead the charge with an NL-best 35 homers. He's slashing .257/.328/.601 for a .929 OPS and 85 RBI in 2025.

Diamondbacks vs Astros Bullpens

The Astros have an excellent 3.31 relief ERA, third-best in the majors.

Closer Josh Hader has a 2.42 ERA and is 25-for-26 in saves, blowing his first of the season on July 12. Setup men Bryan Abreu and Bryan King have 1.87 and 2.70 ERAs respectively over 40-plus-inning sample sizes. Good luck.

The Diamondbacks, meanwhile, still have one of the weakest bullpens in MLB.

Their relief ERA is an ugly 4.93, although they've received (mostly) quality innings from their relievers to open the second half.

Arizona did not have to dip too heavily into what's left of their leverage group in their previous series, getting quality length out of their starters, as well as long-men Anthony DeSclafani and Jake Woodford.