A sweep changes everything: Cardinals-Diamondbacks series' impact on playoffs

The upcoming three-game series between the St. Louis Cardinals and Arizona Diamondbacks, kicking off July 18 at Chase Field, carries major postseason implications as both teams hover near the National League Wild Card threshold. While the Cardinals (51–46) are in a more favorable position, the Diamondbacks (47–50) view this series as a lifeline to reinvigorate their playoff hopes.

Pitching Matchups:

Experience vs. Urgency. Expect Merrill Kelly to start one of Arizona’s games; he’s historically handled the Cardinals well, posting a 3-1 record and a 2.75 ERA over six outings, and a 3.34 ERA overall. St. Louis likely counters with Sonny Gray (9–3, 3.50 ERA), the club’s most consistent starter. The Cards own a modest edge in bullpen stability, while Arizona’s relief corps remains vulnerable with a 4.94 ERA—the fourth-worst in MLB.

 Offensive Firepower and X-Factors

Eugenio Suárez headlines Arizona’s lineup with 31 home runs and 78 RBIs, ranking fourth in MLB for homers. His raw power can change games despite a .222 average. Corbin Carroll adds dynamic speed with 21 homers and 10 triples, and Geraldo Perdomo (.370 OBP) sets the tone with disciplined plate appearances.

The Cardinals counter with a more balanced attack. Brendan Donovan (.297 AVG) enters with a four-game hitting streak, while Alec Burleson (.293 AVG) contributes quietly but effectively against right-handers. Willson Contreras leads the team in power (12 HR, 55 RBI), though his bat has cooled recently.

Venue & Recent Trends

Chase Field hasn't been kind to visiting teams—or the Cardinals, who hold a 22–26 road record and dropped seven straight road games to NL opponents earlier in the season. Arizona is only slightly better at home (23–25). However, St. Louis has won four of its last five head-to-head matchups against Arizona.

The Impact of a Sweep

If the Cardinals sweep, they’d jump to 54–46 and likely be right there for the final Wild Card spot. That could pivot the front office into deadline buyers, targeting bullpen depth or a right-handed bat. It would also quiet trade speculation around veterans like Sonny Gray and boost morale both in the clubhouse and among fans.

For Arizona, a sweep would elevate them to 50–50, reviving their playoff viability and possibly deterring a sell-off. GM Mike Hazen has hinted at running out of time to justify buying, so three wins could prompt him to keep key contributors like Kelly and Suárez, or at least increase their market value if dealt.

Series Outlook

Arizona’s offense (5.08 runs/game, .444 SLG) will challenge St. Louis’ pitching. What this series features is the Diamondbacks, who have hit the fourth-most home runs this season, going up against a pitching staff that has given up the fourth-most. That is not a formula for success if you are the Cardinals.