OAKLAND -- The Mariners weren't fast enough to keep up with the A's on Sunday.
Seattle recorded five hits, sent eight runners to the plate and loaded the bases twice in the second inning but mustered only two runs because of its deficient speed.
The Mariners' inability to capitalize that inning, combined with an offensive onslaught by the A's late in the game against a floundering bullpen, resulted in a loss in Sunday's series finale at O.co Coliseum. Seattle (31-39) fell, 10-2, to Oakland (42-29) to drop back down to 10 1/2 games behind the first-place A's in the American League West after winning the first two games of the series. The Mariners have yet to sweep a series this season.
Oakland displayed greater horsepower around the basepaths, turning modest hits into a triple and double in the second and third innings, respectively. Two innings later, catcher John Jaso scored from first on a double from Yoenis Cespedes for the A's go-ahead run, with Cespedes scoring one batter later off a single -- the eighth hit yielded by Hisashi Iwakuma of the game.
"We were still in the ballgame," Mariners manager Eric Wedge said. "We just didn't answer them. We have to go back and forth with them and answer when that happens."
Iwakuma allowed four runs on the day to snap Seattle's streak of eight consecutive quality starts by Mariners pitchers. They entered Sunday having surrendered only two runs in the last six games.
The Mariners' All-Star candidate hadn't allowed an earned run in his previous 31 1/3 innings, but he struggled from the beginning against the A's, allowing runners to reach second base or beyond in each of his first four innings. He eclipsed 60 pitches midway through the inning and ended his outing with 92 pitches through five innings.
"They were being very aggressive from early in the counts and that got to me," Iwakuma said. The right-hander was in trouble early and often, tossing the ball high in the zone and rarely making first-pitch strikes.
Shaky starts led to high pitch counts for both starters. A's starter Bartolo Colon allowed the five hits in the second before reverting back to the form he's displayed during his six-game winning streak. He retired 15 of the next 16 batters following the two-run second.
"He got stronger throughout the game," Mariners catcher Mike Zunino said. "He was working the bottom of the zone, expanding, trying to do what he can do. He threw a lot of strikes today and got a lot of outs and a lot of ground-ball outs."
Seattle's bats simply vanished, but Oakland's were heating up. In the seventh, the Mariners went down in order with three straight ground balls to shortstop Adam Rosales, while the A's hit back-to-back towering home runs off reliever Blake Beavan.
"You don't want to stop against a team like that that's been swinging the bat well all series," said A's right fielder Josh Reddick, who had a career-high-tying four hits for Oakland and intimidated Zunino from tagging from third base on a flyout in the second inning.
The Mariners' recently defective bullpen reared its head once again to continue the trend started by Iwakuma. Tom Wilhelmsen, who was demoted from the closer's role Friday because of his four blown saves since May 20, replaced Beavan in the middle of the inning but couldn't shut the door on the A's attack.
He immediately loaded the bases by giving up an single and walked in a run in the next at-bat, later allowing a sacrifice fly for the A's eighth run of the day. Carter Capps wasn't any better, surrendering two home runs in the eighth.
"When you know you can turn the ball over with a lead it gives you confidence," Zunino said. "It's one of those things that as a group we have to be a little bit better."
The Mariners, who haven't scored more than four runs in 10 games, have waited all week for their hitting and bullpen to rise to the play of their starting pitching. Instead, it was Iwakuma who mirrored the two, creating a trifecta of dismal play as they continue middling as third place in the AL West standings.
Jeff Kirshman is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.