Diamondbacks' Road Suddenly Gets Much Tougher with Mariners Matchup

The Arizona Diamondbacks are coming of an 11-2 stretch against the Rockies and Giants, running their record up to 31-24.

Diamondbacks Surge Into Playoff Position

Ketel Marte points to his teammates as he scores a run versus the Giants — May 25, 2026; San Francisco, California, USA; Arizona Diamondbacks second baseman Ketel Marte (4) gestures as he scores a run against the San Francisco Giants during the fifth inning at Oracle Park. Mandatory Credit: Kelley L Cox-Imagn Images | Kelley L Cox-Imagn Images

That puts them in a tie with the San Diego Padres for the first NL Wild Card position. They're also 4.5 games back of the Los Angeles Dodgers in the NL West.

This stretched was fueled in large part by the resurgence of Ketel Marte, who won NL Player of the week last week, and then followed that up by going 7-for-15 with a homer and five RBI versus the Giants.

Now the D-backs are off to the Emerald City to play the Seattle Mariners for a three-game interleague matchup. The last time they were in Seattle was in April of 2024 when they dropped two out of three games.

The Mariners are a Tougher Opponent

Julio Rodriguez watches his homerun vs A's on swing follow through May 27, 2026 West Sacramento CA — May 27, 2026; West Sacramento, California, USA; Seattle Mariners center fielder Julio Rodriguez (44) looks on after hitting a three-run home run against the Athletics in the eighth inning at Sutter Health Park. Mandatory Credit: Cary Edmondson-Imagn Images | Cary Edmondson-Imagn Images

The Seattle Mariners have a 28-29 record, but that's good enough for first place in the AL West. The American League only has four teams over .500 at the moment. The Mariners are on a three-game winning streak, however, and are 6-4 in their last 10 games. They have a +24 run differential, compared to +14 for the D-backs.

Star center fielder Julio Rodriguez is heating up after his annual slow start. He has two homers in his last four games and has his OPS+ up to 118 on a .258 B.A. and .754 OPS. Overall the Mariners are batting .268 in their last six games with eight homers and have scored 30 runs, or five per game.

All that is to say that despite their sub-.500 record, the Mariners should be viewed as a good team that went deep into the Postseason last year, and are now rounding into form after a slow start. They are without Cal Raleigh however, who is on the injured list with an oblique strain.

Diamondbacks-Mariners Pitching Matchups

Friday, May 29, 7:10 p.m. MST

Zac Gallen and George Kirby stats through May 28 | Jack Sommers

Zac Gallen has struggled for a large portion of 2026, as evidenced by his 4.80 ERA and poor peripherals to match. But his last two outings versus the Rockies and Giants have looked better. He allowed five earned runs in 11.1 innings across those two starts.

George Kirby has a 3.54 ERA, and has been averaging over six innings per start. Despite T-Mobile park being an extreme pitcher's park, his home ERA is 3.79 versus a 3.23 road ERA. Kirby has allowed nine earned runs in his last 11.2 innings pitched, so perhaps the D-backs are catching him at the right time.

Saturday, May 30, 7:10 p.m. MST

Ryne Nelson and Bryan Woo stats through May 28 | Jack Sommers

Ryne Nelson continues to turn his season around after a bumpy April. His last outing was a career best eight-inning gem against the Rockies. In five May starts he has a 2.36 ERA

Bryan Woo is probably the Mariners' best starter, even though his ERA is slightly elevated at 3.82. His 3.12 xERA and 3.20 FIP speak to the quality of his underlying peripherals. He was knocked around a bit by the Royals in his last start, however, giving up four runs in 4.2 innings on six hits and two walks.

Sunday, May 31, 1:10 p.m. MST

Merrill Kelly, Bryce Miller and Luis Castillo stats through May 28 | Jack Sommers

Merrill Kelly has gone at least seven innings in three of his last four starts. Most recently he went seven against the Giants on May 25, allowing just two runs. Kelly said afterwards it was as good as his stuff has felt all year. That's doubly impressive, as he threw a nine-inning complete game at Coors Field on May 15, his first ever.

The Mariners are going with a "piggyback" system for this spot in the rotation, combining Luis Castillo and Bryce Miller into one game. As the veteran Castillo (5.90 ERA) has struggled, manager Dan Wilson and GM Jerry Dipoto have opted to try to this system over the last few games.

Miller has a 2.25 ERA in his last three games. Expect him to go four or five innings at most, with Castillo coming in to finish up the game if possible.

Diamondbacks vs Mariners Bullpens

Paul Sewald delivers a pitch agains the San Francisco Giants May 26, 2026 — May 26, 2026; San Francisco, California, USA; Arizona Diamondbacks relief pitcher Paul Sewald (38) delivers a pitch during the ninth inning against the San Francisco Giants at Oracle Park. Mandatory Credit: Neville E. Guard-Imagn Images | Neville E. Guard-Imagn Images

The Diamondbacks' bullpen continues to exceed expectations. The D-backs rank 17th in MLB with a 4.11 reliever ERA. But if you take out position player James McCann from the equation that drops to 3.94

Closer Paul Sewald has converted 14 of 15 save opportunities, picking up his 100th career save on Wednesday. He's lowered his ERA to an acceptable 3.80 after some blowups in tie games that led to four losses. His 2.84 xERA hints at some good batted ball metrics despite allowing four homers.

The Diamondbacks rank seventh-best in MLB in stranding inherited runners, having allowed 25% to cross the plate. League average is 30%.

The Mariners, meanwhile, have the sixth-best bullpen ERA in MLB with a 3.16 mark. They also rank best in MLB with just 16% inherited runners scored rate.

Closer Andres Muñoz might be the weak link in their bullpen, surprisingly, as he has a 4.79 ERA and three blown saves in 12 opportunities.

The rest of their core, including Jose Ferrer (1.80 ERA, 3 saves) Eduard Bazardo (2.22 ERA) Cooper Criswell (3.33 ERA) and Matt Brash (0.00 ERA in 13 innings) have gotten solid results. Brash was activated from the IL (lat inflammation) on May 20, and has pitched only twice since then.

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