The Orioles have made a habit out of turning unheralded opposing starters into virtuosos this season.

After one shaky inning, the Orioles did it again Wednesday night, this time to one of their minor league castoffs who couldn't crack the big league rotation last year.

Seattle right-hander David Pauley, who spent all last season stuck at Triple-A Norfolk, was effective through six innings, and the Mariners' bullpen held on to beat the Orioles, 6-5, in the season finale between the teams with the worst records in the American League.

Before an announced crowd of 11,213 on a soggy evening, the Orioles nearly clawed back for another late-inning rally. But Seattle closer David Aardsma (24 saves) struck out Brian Roberts and induced a come-backer from Nick Markakis to strand the tying run at second in the ninth.

The Orioles (42-79) have lost five of their past seven games after winning eight of their first nine under new manager Buck Showalter. It's the club's second consecutive series loss, and it dropped them to 3-6 this season against the struggling Mariners (48-73).

"It's frustrating," Showalter said of losing to Pauley. "You can watch all the tape you want to watch, but … you don't go into it thinking this is a guy you should do this or that" to. "You see that a lot [from] guys who are unheralded, so to speak, so far, but I don't take anything away from his performance."

Although the offense might have followed a familiar script, Orioles starter Jeremy Guthrie veered from the story of his second half.

In his previous four starts, covering 28 innings, Guthrie had allowed just four total earned runs.

On Wednesday, against the worst-hitting, lowest-scoring team in the AL, Guthrie surrendered six runs (five earned) in eight innings.

It was his first rough outing since the All-Star break, halting a streak of six straight quality starts.

It began well, with a perfect first, and the Orioles' offense handed him a 2-0 lead in the bottom of the inning on Luke Scott's two-run single.

But Guthrie (7-12) handed the lead back in the second, courtesy of another big swing from the Mariners' longest name.

Guthrie allowed a leadoff double and an infield single to start the second. But a good, diving stab by first baseman Ty Wigginton and a strikeout made it two outs when left fielder Matt Tuiasosopo came to the plate.

Tuiasosopo had a homer and drove in all four of Seattle's runs in a 4-0 win Tuesday. On Wednesday, he smashed Guthrie's 85 mph slider into the left-field seats to wipe out the Orioles' early lead.

In five total at-bats Tuesday and Wednesday, Tuiasosopo had two homers and seven RBIs. He had one homer and two RBIs in his previous 71 at-bats this season.

"The most disappointing thing was not winning the game," Guthrie said. "I had a shot there; I gave myself an opportunity with the strikeout to the hitter before him and just didn't execute the pitch. He hit the exact same pitch yesterday. He proved he can hit it back-to-back nights, and it's my fault for throwing it there."

Guthrie kept the Mariners off the scoreboard for three more innings before Josh Wilson led off the fifth with a single and scored when Ichiro Suzuki laced a double down the right-field line. Suzuki took third when right fielder Nick Markakis failed to pick up the ball cleanly.

Suzuki scored on a sacrifice fly. Seattle added its sixth run in the eighth against Guthrie on Casey Kotchman's RBI ground-rule double.

Pauley, who entered the night 1-4 with a 3.31 ERA in 11 games with the Mariners, allowed two runs in the first inning.

He then shut down the Orioles' offense, retiring 13 straight before Roberts doubled to lead off the sixth. The Orioles stranded him there -- failing to get a ball out of the infield.

"Off a guy like him, you can go up there and be patient," Markakis said of Pauley. "He's a location guy, puts pitches where he wants it. Go up there take a couple pitches, see a couple pitches. He's got good movement on his ball, he's got late movement and it's tough to pick up at the last second. He made some pitches, and we didn't score enough runs to win the game. That's it."

Pauley (2-4) went out to pitch the seventh but was chased after giving up Matt Wieters' 10th homer of the season, a two-run shot.

The Orioles climbed within one in the eighth when Scott doubled, moved to third on a balk by Jamey Wright and scored when Wright threw a wild pitch. But Tuiasosopo ended the eighth with a diving catch in left.

In the bottom of the first, the Orioles immediately jumped on Pauley, who was 9-12 with a 4.37 ERA for the Norfolk Tides in 2009 after the Orioles acquired him from the Boston Red Sox for reliever Randor Bierd. He left in the offseason and signed a minor league deal with the Mariners.

To lead off the game, Pauley walked Roberts, who stole second and moved to third on Markakis' single up the middle.

Roberts attempted to score on a grounder by Wigginton, but Mariners third baseman Jose Lopez went home with the throw and trapped Roberts in a rundown. Roberts was tagged out by Pauley, but not until after Markakis and Wigginton had moved up to second and third.

Scott then hit a two-run single to left. Pauley followed by hitting Adam Jones with a pitch, but Felix Pie grounded into a double play to end the first.

And Pauley, the castoff turned temporary virtuoso, took over from there.

dan.connolly@baltsun.com

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