The Arizona Diamondbacks return to Chase Field on July 18 with a 43–43 record and a golden opportunity to gain traction in the tightly packed National League playoff race as they host the St. Louis Cardinals in a matchup that highlights their offensive firepower and home-field potential. Though Arizona has been uneven over the last few weeks, particularly with a 2–4 mark in their most recent homestand, they continue to pose a consistent threat thanks to a dynamic offense led by Eugenio Suárez, Josh Naylor, and Corbin Carroll. Suárez has clubbed 31 home runs so far this season, bringing the kind of instant offense that can shift momentum with one swing, while Naylor’s .357 OBP and ability to drive in runs from the middle of the order has made him one of the Diamondbacks’ most valuable bats. Carroll, despite a bit of a sophomore slump compared to his breakout 2023 campaign, remains a disruptive force on the bases and in the outfield, giving Arizona speed and energy at the top of the lineup. Arizona’s game plan is built around early run production, aggressive base running, and forcing opposing pitchers into high-stress innings—a recipe that aligns well with their starting pitcher for this game, ace Zac Gallen. Gallen, who opened the year as the team’s most trusted starter and signed a lucrative $13.5 million deal, continues to deliver quality innings when healthy, using his fastball-curveball combination and sharp command to navigate lineups efficiently.

However, his recent outings have been somewhat inconsistent, and Arizona knows they’ll need him to go at least six innings to protect their vulnerable bullpen, which has been a major weak spot this season. The relief corps, headlined by closer Paul Sewald and setup man Kevin Ginkel, has posted one of the highest ERAs among NL playoff contenders and has repeatedly struggled to maintain leads in the seventh through ninth innings. That puts extra pressure on the offense to build a cushion, especially against a Cardinals team that has a knack for staying close and clawing back late. Defensively, the Diamondbacks are one of the sharper clubs in the league, with Carroll and Alek Thomas covering tons of ground in the outfield and the infield flashing good hands and athleticism across the board. At Chase Field, Arizona typically enjoys a slight offensive boost thanks to the stadium’s friendly dimensions and lively surface, and they’ll look to exploit that edge by jumping on whichever mid-rotation starter St. Louis deploys—likely a contact-reliant pitcher like Mikolas or Matz. If Arizona can execute their typical formula—early runs, steady starting pitching, and just enough from the bullpen—they have the advantage to win this opener and set the tone for the weekend series. But if Gallen gets chased early or if the bullpen is forced to cover too many outs, things could unravel quickly. The Diamondbacks will look to their core hitters to set the tempo, generate rallies, and give Gallen a lead to protect, which remains their most dependable path to victory at home in a must-win series opener.