New York beat the Mariners in the series-opener on Friday, 3-2, on a night when Seattle stranded 19 runners.
That wasn't the case Sunday, when the Mariners had no problem pushing runs across. Seattle (41-19) was led by the six-hit day of Ichiro Suzuki, who raised his average to .328 by the end of the day, and helped the Mariners win 13-1 and 7-0.
The Mets (27-33) two losses dropped the team to 15 games behind National League East leading Atlanta, which beat Pittsburgh earlier in the day.
Leiter (6-3) only lasted two innings as the Mariners put up four runs in each of the first two innings, tagging the left-hander for nine hits.
Up 8-0 entering the bottom of the second, Garcia cruised to his first complete game in 13 starts this season.
He gave up just six hits and one run, a solo homer to Cliff Floyd in the fourth, to improve to 6-6 on the year. Garcia also struck out seven while walking just one.
Not needing any more help, he got some anyway when Mike Cameron hit a two-run single with the bases loaded and nobody out in the fourth inning. Three batters later, with the bases reloaded after a Jeff Cirillo walk, Ben Davis ripped another single up the middle of the infield to score two more.
That made it 12-0 after four innings, and had the Shea Stadium crowd snoozing until the first pitch of game two.
But once the night-cap started, it was more of the same for the home fans wearing the blue and orange.
The Mariners' offense erupted again in the early innings, scoring twice in the first on a Carlos Guillen RBI double and a Mike Cameron RBI single, and again once more in the second.
That was more than enough for the veteran Moyer, who shut down the Mets through seven innings of work. He limited the New York batters to two hits and didn't give up a run, becoming the first 10-game winner in baseball at 10-2.
Bacsik (0-1) took the loss, his first decision of the year, giving up 11 hits and five runs over five innings.
Floyd was the lone Met to record two hits on the day, going 2-5 with his 15th double and 12 homerun of the year.
Meanwhile, eight Seattle batters had at least two hits.
Run to the Border: In one of the more humorous moments of the season, Mariners' manager Bob Melvin sent 40-year-old Pat Borders into the game as a pinch-runner to replace Edgar Martinez, who had a pinch-hit single.
Streaking: Bret Boone recorded hits in each game, going 2-3 in the opener and 1-4 in the night-cap, lengthening his hitting streak to 14 games.