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Kevin Millwood's return to Camden Yards was reminiscent of his one dreadful season as a member of the Baltimore Orioles.

Millwood gave up seven runs in four innings, and the Seattle Mariners dropped a 9-2 decision Wednesday night for their fourth straight defeat.

The 37-year-old Millwood pitched for Baltimore in 2010, going 4-16 with a 5.10 ERA in 31 starts. During that season he received the second-worst offensive support in the AL, a meager 3.28 runs per game.

Seattle managed only two runs in this one, but much of the blame for this loss belongs to Millwood (4-10), who gave up two home runs for the first time this season.

"I didn't pitch very good today," the right-hander said. "No fun to stink. We didn't play well here at all."

The Mariners' four-game skid began in Yankee Stadium and continued in Baltimore, where they were outscored 20-10 during the Orioles' three-game sweep.

"Tonight is the first night we didn't play well," manager Eric Wedge said. "We played well in New York and last night (a 14-inning loss) was a battle.

"We're working through some things here," Wedge said. "We have a couple of new guys, and we have to take an opportunity to see what they can and cannot do."

Newcomers such as pitchers Carter Capps and Stephen Pryor, along with position players Eric Thames, Trayvon Robinson and Mike Carp have become part of Seattle's post-Ichiro Suzuki era. Wedge can only hope to get some chemistry and a few wins from his last-place win over the season's final two months.

Very little went right Wednesday night, as Seattle fell behind 7-0 in the fourth inning and stumbled to the finish.

Steve Johnson (1-0) gave up two runs, five hits and two walks over six innings for Baltimore in his first major league start and second appearance. The 24-year-old was recalled from Triple-A Norfolk to sub for Tommy Hunter, who was scratched because he threw in the bullpen Tuesday night in anticipation of entering a game that lasted 14 innings.

Johnson grew up in Baltimore and is the son of former Orioles pitcher Dave Johnson, who now works for the team's TV network. Steve Johnson's debut as a starter came exactly 23 years after his father made his first career start in Baltimore, a complete-game win against Minnesota.

"It was great and it was unbelievable. Words really can't explain," Steve Johnson said. "I know a lot of people texted me and said they were coming. A lot of people from my high school and people I went to high school with. It was great."

Matt Wieters tied a career high with five RBIs, Nick Markakis and Mark Reynolds homered, and Adam Jones had three hits for the Orioles.

Johnson blanked Seattle on three hits through five innings before giving up a two-run homer to Kyle Seager in the sixth. It was Seager's team-high 13th homer, the second in two nights.

Johnson needed only six pitches to strike out the first two batters in the first inning, then went to 0-2 on Jesus Montero before giving up a single. Johnson followed that with a three-pitch strikeout of cleanup hitter John Jaso.

Baltimore went up 2-0 in the bottom half. With two on and two outs, Wieters hit a liner to right that sent Thames running toward the wall. As he leaped to make the catch, the ball popped out of his glove for a two-run double.

Seattle used a single and two walks to load the bases with one out in the second, but Johnson worked out of trouble.

The Orioles made it 4-0 in the third. Markakis led off with a triple and scored on a single by J.J. Hardy, who took third on a double by Jones and came home on a groundout by Wieters.

In the fourth, Reynolds hit a solo shot, Omar Quintanilla singled and Markakis drove a 1-2 pitch over the right-field wall. Millwood got the final two outs but did not return for the fifth.

Wieters hit a two-run double in the seventh off Josh Kinney.

NOTES: The Orioles placed INF Ryan Flaherty on the 15-day DL with a bacterial infection and recalled RHP Miguel Socolovich to strengthen the bullpen after Tuesday night's marathon. ... Seattle has a day off Thursday and will face the Los Angeles Angels on the road Friday. Baltimore opens a three-game series against the Kansas City Royals on Thursday night. ... Seattle's Michael Saunders went 0 for 14 with seven strikeouts in the series.