SEATTLE (AP) — Bob Melvin is still trying to figure out what happened to the consistency Oakland had the first month of the season.

It’s clearly gone now after Oakland lost its fifth straight on Friday night, a 6-3 loss to the Seattle Mariners that dropped the Athletics below .500 for the first time since beginning the season with one win in their first three games.

“Everything. Offensively, we’re not as good as we were early. We’re getting behind. We’re putting our team in a hole. Defensively, we didn’t have any errors today. We had some plays that affected the game early on,” Melvin said. “Everybody has to pick everybody up and we’re not doing that right now. We’re struggling.”

Seattle starter Hisashi Iwakuma retired 16 straight over one stretch of a solid seven-inning outing, Raul Ibanez homered for the first time in nearly a month as the Mariners won for the eighth time in 11 games and continued a miserable road trip for the A’s.

It started with Oakland taking two of three from the Yankees, but the A’s were swept in Cleveland and didn’t get anything started against Iwakuma until they were already in a 6-0 hole.

“Facing him as a hitter, I knew what he was going to be throwing and I still went after it,” Oakland’s John Jaso said. “He was real deceptive.”

Making just his fourth start, Oakland’s Dan Straily (1-1) struggled to get through five innings, but didn’t get help from his defense starting in the first inning that led to two runs. Kendrys Morales’ chopper to left side bounced past both third baseman Josh Donaldson and Lowrie at shortstop to put runners at the corners with one out instead of a possible inning-ending double play. Michael Morse followed with an RBI single and Justin Smoak lined an RBI double to give Iwakuma an early lead.

But Straily was lamenting the one pitch to Ibanez that was left too high in the strike zone with two outs in the third inning. Despite being out front on the swing, Ibanez was able to get his barrel on the pitch and lift it out to right field for his first homer since April 14.

The inning was kept alive by a two-out walk to Smoak. Ibanez’s homer broke the game open and gave Iwakuma a comfortable margin to work with.

“The whole outing was based off of one changeup left up and Ibanez took it out. That was the final score right there,” Straily said. “If I make that pitch and he rolls it over, it could have changed everything. I can’t make that one mistake.”

Iwakuma (4-1) took a one-hitter into the sixth inning before running into trouble, putting together another strong outing to help cement himself and Felix Hernandez as one of the top rotation duos in baseball. Iwakuma has allowed five earned runs over his last five starts, and the number could have been even smaller if not for a scoring change that ended up tagging him with two earned runs against the A’s.

Overshadowed by Hernandez, the ace of the Mariners staff, Iwakuma has been nearly as solid this season. He’s pitched at least six innings in seven of eight starts despite being bothered by a lingering blister on his pitching hand, and has not allowed more than three earned runs in any start.

Iwakuma gave up a solid leadoff single to right field to Jaso and then was unhittable for the next five innings. He set down 15 straight with remarkable ease, through a combination of broken bats, weak groundballs and lazy flies. He struck out Yoenis Cespedes to close the first, struck out Derek Norris and Jaso in the third and retired Josh Donaldson and Daric Barton swinging to end the fifth.

Iwakuma’s streak finally ended at 16 straight retired when Eric Sogard reached on an infield single — originally ruled an error — with one-out in the sixth inning. His groundball bounced off the arm of shortstop Brendan Ryan and Sogard reached without a throw. Jaso followed with a bloop single, and the A’s finally got to Iwakuma on Jed Lowrie’s two-out, two-run double into the right-field corner. Lowrie had just one RBI in his previous 17 games before the double.

“He repeats. He’s so consistent with his delivery, his arm action, his arm slot, release point, it’s tough to see what is coming out,” Seattle manager Eric Wedge said. “That’s what you have to do. If you’re going to be a solid starting pitcher up here you’ve got to do that.”

NOTES: Seattle improved to 16-8 this season when its starting pitcher works at least six innings. They are 1-11 when the starter fails to get through six. ... Seager scored three of the four times he reached base. ... Norris hit a solo homer, his first of the season, in the eighth off Seattle reliever Oliver Perez.