Pineda struck out the first five batters and the Angels never touched the hard-throwing 22-year-old until a leadoff single in the third. But things unraveled quickly after that, as Torii Hunter ripped a pair of home runs and racked up five RBIs in one of the first rough games Pineda has endured this season.
The seven runs were the most allowed in Pineda's 18 starts, as he fell to 8-6 with a 3.03 ERA.
Seattle racked up 12 hits off Joel Pineiro and the Angels' bullpen, but Los Angeles did bigger damage with its own dozen blows, thanks largely to Hunter's 10th and 11th home runs of the season. Mark Trumbo added a home run in the eighth off reliever Chris Ray, giving the Angels seven long balls in the past two nights.
The Mariners' pitching staff came into the game with the lowest pre-All Star ERA in franchise history at 3.15, and hadn't allowed nine runs in a game since April 23, in a 9-1 loss to the A's.
The fourth straight loss dropped Seattle to 43-47, and it'll look to Felix Hernandez to stop the bleeding -- and avoid a sweep -- in Sunday's 12:35 p.m. PT series finale against Dan Haren. It's the first time the Mariners have been four games under .500 since May 20 at 20-24.
Manager Eric Wedge wasn't around to watch Pineda's undoing, as the skipper got ejected on what turned out to be a critical play in the bottom of the third when Hank Conger walked on a full-count checked swing that could have been a double play when Miguel Olivo appeared to have thrown out Trumbo stealing second.
Instead, Conger was awarded first base, Trumbo got to stay at second and Wedge was sent packing by third-base umpire Sam Holbrook after yelling from the dugout.
That whole scenario loomed larger when highly regarded Angels prospect Mike Trout followed with his first Major League hit on a bunt single, with Pineda's throw arriving at first base at the same time as the runner. Pineda was charged with a throwing error when the ball got away from Dustin Ackley covering first, with Trumbo crossing the plate for the first run.
One out later, Hunter ripped a three-run blast to left field and Pineda was staring at a 4-0 deficit.
The Mariners countered with three runs off Pineiro over the fourth and fifth innings to cut the lead to one, but Hunter capped a three-run response in the bottom of the fifth with his second blast, this one a two-run shot to right field.
Jeff Gray replaced Pineda in the sixth, his first appearance for Seattle since June 11, and gave up one run in two innings.
The five innings matched Pineda's shortest stint of the season, though he maintained his streak of having gone at least five frames in all 18 starts, the 10th longest stretch to start a career in Major League history.
The Angels are now 15-2 in their last 17 home games against Seattle, and have the best record in the Majors since June 13 at 18-6. Seattle slipped further behind in the American League West race, as front-running Texas topped Oakland and now owns a 6 1/2-game lead over the third-place Mariners.
The Mariners started five rookies in the game, including Pineda. Three of those rookies -- Ackley, Carlos Peguero and Greg Halman -- each had two hits. The other, third baseman Kyle Seager, went 0-for-4 and remains hitless in 10 at-bats in his first three games.