Designated hitter Bryan LaHair ended the run famine with a two-run home run to right-center in the second inning, and Kenji Johjima added a two-run shot in the sixth as Seattle built a pair of three-run leads.
But starter Carlos Silva encountered more back problems and departed in the fourth inning, the Mariners' bullpen sprung a leak and the seven-run outburst wasn't enough to end what has now become a 10-game losing streak.
"We lost that game four different times, really," Riggleman said. "But I thought we had a man on third with nobody out."
That would be second baseman Luis Valbuena.
He greeted Athletics closer Brad Ziegler with a line drive into the right-field corner and sprinted around the bases, destined to wind up with his first career triple. He slid into the base before the relay throw landed in Daric Barton's glove.
What happened next was debatable.
It appeared to the Mariners that Valbuena's head-first slide enabled him to reach the base before the tag, and television replays showed that the runner's right hand touched the base, but then came off. His left hand also was in the vicinity of the base, but replays did not show exactly when the tag was applied.
"I had the guy sliding in and the third baseman's foot was blocking the base," third-base umpire Bill Miller told a reporter after the game. "The guy's hand never reached the base and that's why he was called out. He went in with his left hand and Barton blocked his hand from touching the base. The tag was very late, but when he was tagged, he was off the base."
Mariners third-base coach Sammy Perlozzo immediately voiced his disapproval with the call and finally had to be led away from the umpire. Riggleman gave his opinion -- several times -- and was tossed.
"I don't want to say too much abut it," the manager said. "That's a good crew and Miller is a good umpire. From a distance, I was surprised by the call. From 200 feet away I can't see [the play]. I saw that [Valbuena] beat the throw and assumed he was safe. I was shocked when he was called out. I thought we had a man on third with nobody out."
Instead, Ichiro Suzuki walked and shortstop Yuniesky Betancourt grounded into a game-ending double play on the first pitch.
Scoring seven runs on any given day during this 11-game road trip would have been enough to win eight of those games and remove any chance of reaching the 100-loss mark.
But with 97 losses and eight games remaining, it doesn't look good.
Seattle built an early 5-2 lead against the Athletics, but it was sliced to a one-run gap off Silva, who still has just one win since the end of April. Silva exited in the bottom of the fourth inning after a walk, his own error and back-to-back singles produced two runs. Lefty reliever Cesar Jimenez came in and induced Bowen to bounce into an inning-ending double play.
Silva's error on a bunt attempt snapped a streak of 162 consecutive fielding chances without committing an error, a streak that started on May 27, 2004, and was the longest current streak among active pitchers.
Jeff Baisley's second two-run single of the game off Silva prompted the first of four pitching changes by Riggleman.
"Starting somewhere around the second inning, we got word from the trainer that something was going on with Silva's back," Riggleman said. "Basically, it was the same thing as before. He wanted to go back out, which he did, and put a zero up [in the third inning]. His velocity was up, but he couldn't get the ball down. I watched his face to see if there was any indication of pain and I thought he looked uncomfortable.
"At that point, we had to make a decision for him."
The first pitching change worked well -- for almost two innings.
Jimenez worked a scoreless fifth inning and the Mariners extended their lead back to three runs when Johjima belted a two-run home run to left field, his sixth of the season. But Jimenez yielded consecutive singles to start the bottom of the sixth inning, and then struck out Jack Hannahan.
Playing the percentages with a three-run lead, Riggleman replaced the left-handed Jimenez with right-handed Roy Corcoran. Two pitches later, the Athletics scored three runs and tied the game at 7.
Corcoran, who has been one of the most dependable relievers this season, has stumbled in his last three outings, surrendering five earned runs in 2 1/3 innings.
"When you go to the bullpen, you have got to get the first out," Riggleman said. "If he doesn't get the first guy out, it's going to go south from there, and it did. But I made those decisions. It's on me. It was me making those decisions and every one of them blew up in my face."
The Mariners ended their scoring drought at 27 innings, when Miguel Cairo singled to center field with two outs in the second inning and LaHair followed with a no-doubt-about-it home run to right-center, his third of the season.
The third-longest scoreless streak in franchise history started in the second inning of Wednesday night's game against the Royals in Kansas City. After getting all goose-eggs the remainder of that game, the Mariners were shut out for nine innings on Thursday afternoon and nine more on Friday night in the series opener against the Athletics.
The franchise record of 29 straight scoreless innings, set in 2004, still stands.