5 Main Reasons Why Diamondbacks Missed the Playoffs Again

There were many factors at play.

Sep 27, 2026; San Diego, California, USA; Arizona Diamondbacks second baseman Ketel Marte (4) reacts after lining out during the third inning against the San Diego Padres at Petco Park. Mandatory Credit: Denis Poroy-Imagn Images | IMAGN IMAGES via Reuters Connect

The Arizona Diamondbacks will be forced to watch playoff baseball from home, for the third straight season.

On Sunday, they were eliminated from Postseason contention following a win by the Philadelphia Phillies and their own loss to the San Diego Padres.

There are many reasons why this outcome happened. Inside each and every loss — and even some of the wins — one can excavate blame from the wreckage. But there are some factors that stand out above others.

Below are five of the biggest reasons for Arizona's unfortunate early end to 2026:

Diamondbacks' star trio underperforms

Sep 20, 2026; Phoenix, Arizona, USA; Arizona Diamondbacks second baseman Ketel Marte (4) reacts during the first inning against the New York Yankees at Chase Field. Mandatory Credit: Arianna Grainey-Imagn Images | IMAGN IMAGES via Reuters Connect

Ketel Marte, Corbin Carroll and Geraldo Perdomo have all had individual MVP cases in recent seasons, but they did not look like the best version of themselves offensively this year.

Marte had the largest downturn in numbers. He hit .249 and produced a .748 OPS, 135 points down from 2025's .893. He struggled at the plate for a good portion of 2026, and caused external noise during another unexcused absence.

Carroll produced a strong line overall, but a .795 OPS and 22 homers, spurred on by a deep mid-season slump, were his worst since his 2024 sophomore slump. It's worth noting he was banged up for a good portion of the season, however.

Perdomo played elite defense, but saw his numbers plummet from 2025. After placing fourth in MVP voting last year with a 100-RBI, 20-homer campaign, he slashed .262/.370/.377 with just nine homers.

Diamondbacks' unstable starting rotation

Jul 1, 2026; Phoenix, Arizona, USA; Arizona Diamondbacks pitcher Zac Gallen (23) throws against the San Francisco Giants in the first inning at Chase Field. Mandatory Credit: Rick Scuteri-Imagn Images | IMAGN IMAGES via Reuters Connect

The Diamondbacks came into 2026 with an excess of starting pitching. That hardly ever goes according to plan.

Merrill Kelly missed time with intercostal nerve irritation and underperformed to a career-worst 4.94 ERA. Zac Gallen followed up his worst season with an even uglier 6.07 ERA, an elbow injury and an eventual move to the bullpen.

Corbin Burnes' return from Tommy John surgery was pushed back to September due to a shoulder injury. He posted an ERA over 7.00 in three starts when he did return.

Ryne Nelson pitched to a 4.95 ERA and missed significant time with an elbow injury. Michael Soroka spent two stints on the IL. Brandon Pfaadt needed a trip to the minor leagues to return to form.

Arizona had to ask for significant innings from rookies Kohl Drake (6.53 ERA), Mitch Bratt (4.70 ERA) and Jose Cabrera (5.72 ERA). Only Eduardo Rodriguez (2.89 ERA) was both healthy and effective for the entirety of the season.

Diamondbacks' issues with right-handed pitching

Sep 24, 2026; Pittsburgh, Pennsylvania, USA; Pittsburgh Pirates starting pitcher Paul Skenes (30) throws against the St. Louis Cardinals during the fourth inning at PNC Park. Mandatory Credit: Charles LeClaire-Imagn Images | IMAGN IMAGES via Reuters Connect

The majority of arms a team faces in a season are right-handed. The Diamondbacks had an extremely difficult time dealing with righties.

Arizona held the seventh-worst batting average against right-handers (.235). Their 92 wRC+ and .697 OPS against that type of arm are both bottom five.

Ironically, the D-backs destroyed southpaws. They posted a second-best .782 OPS and third-best 114 wRC+ against lefties. It's a shame over 70% of MLB pitchers are right-handed.

Diamondbacks struggle with situational offense

Sep 26, 2026; San Diego, California, USA; Arizona Diamondbacks shortstop Geraldo Perdomo (2) scores a run during the second inning against the San Diego Padres at Petco Park. Mandatory Credit: David Frerker-Imagn Images | IMAGN IMAGES via Reuters Connect

By the numbers, the Diamondbacks' stats with runners in scoring position are actually a slight improvement over 2025. They hit to a .756 OPS with RISP, good for a 103 wRC+.

That's an improvement over 2025's .744 OPS and 100 wRC+ — which led to a 80-82 record — but falls well short of where Arizona's offense sat in 2024, when they won 89 games.

The D-backs hit to a .852 OPS and 131 wRC+ with RISP in that successful season — both first in the majors.

Arizona's 2026 offense, at times, seemed even worse than the numbers suggest. They frequently struggled to score the easy run from second or third base, and struggled to even come away with productive outs. Many runs were left on the field.

Diamondbacks struggle in late, winnable series

Sep 27, 2026; San Diego, California, USA; Arizona Diamondbacks right fielder Corbin Carroll (7) hits an RBI double during the seventh inning against the San Diego Padres at Petco Park. Mandatory Credit: Denis Poroy-Imagn Images | IMAGN IMAGES via Reuters Connect

The Diamondbacks, in the midst of a strong September, wasted two opportunities to gain serious ground in the playoff race.

They could not score enough runs to come away with a series win over the eventual 80-82 Miami Marlins, losing two of three. They also dropped two of three to the Texas Rangers, who struggled with injuries all year and ended 80-82, as well.

It does not come down to just those two series. Arizona lost a series to the 100-loss Rockies in August and were swept by the 76-86 Mariners in May. There were many other examples.

Even the best teams cannot win every series, but the Diamondbacks' inability to handle business against some beatable opponents add up to more than a handful of losses.