"Our starting pitching will take us as far as we can go," manger Scott Servais said. "Kuma was outstanding tonight."
The Mariners used solo homers from Nelson Cruz, Mike Zunino and Adam Lind to beat Rick Porcello, who slipped to 14-3. The sinkerballer turned in his second straight complete game and gave up just one additional hit other than the homers. He walked one and struck out eight.
"I pitched deep into the game, felt like I threw the ball well. Their guy was better," said Porcello. "He really threw the ball well. He was outstanding. You tip your hat, sometimes you run into that."
The loss dropped Boston three games behind the Orioles for first place in the American League East, and a half-game behind the Tigers for the second Wild Card spot. It was the continuation of a tough road trip offensively for the Red Sox, who have scored 21 runs in seven games.
"There's been times where we've used the whole field and there have been other times where that hasn't always been the case," said Red Sox manager John Farrell. "I can't say it's dramatically changed or different from what we've been showing for the better part of this season. Again, we get a couple people on and the timely hit has not been there."
Andrew Benintendi, the highly-touted prospect making his first Major League start for the Red Sox, had a pair of singles.
The Red Sox had the tying run at the plate in the ninth, but Mariners closer Edwin Diaz worked out of a jam, allowing just one run to get the save.
MOMENTS THAT MATTERED M's use the longball: Cruz, Zunino and Lind each hit solo shots to score Mariners' three runs. Cruz started things off by belting a 441-foot home run, according to Statcast™, high into the left field bleachers in the second inning for the first run of the game. The solo blast was Cruz's 27th homer of the season and his 12th in 29 games. Neither team scored again until the sixth when Zunino gave the Mariners a 2-0 lead with his second homer in as many nights. Lind tacked on another run in the seventh with his 16th home run this season.
"Porcello's had a great year and really mixing in all of his pitches," Servais said. "Pitches up in the zone more than he used to. Very effective tonight. He made a couple mistakes and we got on them."
Benintendi's first hit: In his first at-bat of the night, Benintendi slammed a single to left in the top of the third inning. Benintendi went 0-for-2 off the bench in his debut on Tuesday. He wasted no time making his presence felt in his first start, belting an 0-1 fastball cleanly into left. His second hit was a line shot to right in the eighth.
"It felt good to get it out of the way," said Benintendi. "I don't really know how to explain it. Just one of those things you dream about your entire life. Got to first base, and it kind of set in. It was really exciting." More >
Iwakuma's shutout 7: Iwakuma kept the Red Sox, who led the league in runs coming into Wednesday's game, scoreless through 7 1/3 innings. Of the 97 pitches he threw, 73 were strikes. That's more strikes than he's thrown in a single game all season. His impressive outing came right after his worst appearance of the season. He allowed five runs in just 3 innings against the Cubs on July 29. More >
Ortiz honored by original team: Red Sox slugger David Ortiz was honored by his original professional team prior to the game in recognition of his final Major League season. The Mariners brought out Edgar Martinez to present Ortiz with a framed picture of his original contract that he signed with Seattle in 1992. Martinez and Ortiz might be the two best DH's in history.
"That was good. That was special," said Ortiz, who was traded from the Mariners to the Twins for Dave Hollins in 1996.
SOUND SMART WITH YOUR FRIENDS Porcello has gone at least five innings in his last 29 starts, dating back to Aug. 26, 2015. He has gone six innings or more in all but three of those starts.
WHAT'S NEXT Red Sox: Left-hander Drew Pomeranz will try to earn his first win with the Red Sox in his fourth start for his new team. Pomeranz lacked command in his last start, giving up six hits, five runs and two walks over 5 1/3 innings against the Angels. The finale of this four-game series is scheduled to start at 10:10 p.m. ET.
Mariners:Ariel Miranda will take the mound for the Mariners in his first Major League start. Seattle acquired Miranda Sunday from the Orioles for left-handed pitcher Wade Miley. First pitch is scheduled for 7:10 p.m. PT