SF Giants lose to Diamondbacks on walk-off homer by Ketel Marte

PHOENIX - The Giants could only play with danger for so long before they eventually got snakebitten.

Keaton Winn slithered out of a bases-loaded jam in the seventh by inducing an inning-ending double play, and Caleb Kilian did the same thing in the eighth. In the ninth, the Diamondbacks finally bit the Giants’ bullpen. Arizona’s Ketel Marte hit a walk-off, three-run homer on Tuesday night at Chase Field off left-hander Matt Gage, handing San Francisco a devastating 5-3 loss.

“At that point, Kilian had 25 pitches. Went with a fresh arm, different look and made the wrong decision, cost us the game. Not that Gage - he’s got as good of numbers as anybody on our team and he’s gotten it done for us more times than not. Obviously, it’s on me,” said manager Tony Vitello.

While Kilian had already thrown 25 pitches (and allowed a run) when Vitello lifted him, the right-hander was a better matchup for Marte from a splits perspective.

Gage has been one of the Giants’ best relievers this season (1.40 ERA entering play) and employs a deceptive delivery, but Marte has far better numbers against lefties (.892 OPS) than righties (.781 OPS). Another potential option for Vitello would’ve been keeping Kilian in to pitch around Marte, then summoning Gage for the left-on-left. matchup with Corbin Carroll if necessary.

Gage, who recorded his first career save on Saturday against the Athletics, didn’t throw a horrible pitch to Marte either, dropping a slider below the strike zone. Marte, a three-time All-Star, just put a better swing on the pitch before emphatically flipping his bat.

Marte’s three-run homer, the first walk-off of his career, was preceded by home plate umpire Bill Miller calling Susac for catcher’s interference.

With two outs and one on, the Diamondbacks’ Ryan Waldschmidt fouled off an 0-1 four-seam fastball by Kilian as pinch-runner Jose Fernandez attempted to steal second base. Susac emerged from his squat to fire a throw as Waldschmit unfurled a swing, and Miller immediately called the rookie backstop for interference.

The Giants challenged the call, but the call was upheld. Susac said he wasn’t sure if Waldschmidt’s bat hit his glove, citing how he was trying to throw out Fernandez at second base.

“It’s a tough one to lose that one late,” said Susac, who reached base three times with an RBI double, a walk and a single. “Thought we did a really good job of getting out of some jams, but just the way the game goes sometimes.”

Before the ninth, the Giants’ bullpen found a way to wiggle out of danger in the seventh and eighth.

The Diamondbacks began the seventh with a double by Nolan Arenado and a single by Ildemaro Vargas, a pair of hits that knocked starter Landen Roupp out of the game. After striking out Loures Gurriel Jr. and walking Gabriel Moreno, Winn induced an inning-ending double play to escape the jam.

Thanks to Winn, Roupp ended his night having only allowed one run over six-plus innings with three strikeouts.

“He made a pitch, and getting over (to first) is pretty tough, especially on the double play,” Roupp said. “You gotta run over there and then find the bag, and he did a great job with that.”

Kilian entered a perilous situation of his own when Miller only retired one of the four batters he faced in the bottom of the eighth, gifting the Diamondbacks a free rally by walking three batters. Nolan Arenado, who hit a grand slam on Monday, had the potential to flip the scoreboard with one swing, but Kilian induced an inning-ending double play of his own.

“It was an unbelievable effort by those guys defensively, but also some guys coming in and making pitches,” Vitello said of the double plays.

In the ninth, Gage couldn’t wiggle out of one last jam and was responsible for San Francisco’s sixth blown save. The Giants’ bullpen ended April with a 3.19 ERA, the second-best mark in the majors, but that unit has allowed 28 earned runs over 61 innings (4.13 ERA) this month.

“It’s pretty unfortunate, but just got to move on and come out tomorrow and play better baseball,” Roupp said.

First baseman Rafael Devers and shortstop Willy Adames hit back-to-back home runs in the top of the second inning, their sixth and fifth homers of the season, respectively. Along with his homer, Devers doubled and made several slick plays on defense.

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This story was originally published May 19, 2026 at 10:55 PM.