CHICAGO -- The optimism the Pirates had coming into the Interleague portion of their schedule had been sucked out of the clubhouse by the time Thursday's 13-8 loss to the White Sox at US Cellular Field was in the books.

"It's depressing, a series like that," Adam LaRoche said, summing up the collective sentiment.

It was depressing because this year, Interleague Play was supposed to be different. The Pirates had better designated hitter options. Their starters were cruising with more consistency. The team's new gritty mentality supported the belief that it wasn't going to be overmatched.

But after coming into this two-city swing with the Majors' worst Interleague record at 57-94, they have only further distanced themselves with that distinction by finishing the trip 1-5. And after being able to nearly taste .500 for the first time since mid-April, the club now finds itself five games under for the first time since May 7.

They have a surging White Sox team to thank for that.

"You can't put the fault too much on our guys," shortstop Jack Wilson said. "These [Chicago hitters] don't swing at balls, and they can hit. They outdid us this series."

As deflating as this week-long stretch was, the fact that the Pirates were actually in solid position to turn their Interleague fortunes around for the better makes the taste that much more bitter.

Consider what the results of this road trip could have -- and in the eyes of the players, based on comments made after Thursday's loss -- should have been.

There was the five-run lead that Dumatrait squandered in the opening game of the trip, a game in which the Pirates watched Baltimore score eight unanswered runs. That game was followed by two more in which the Bucs blew ninth-inning leads. They were fortunate to at least split those two games.

"It's a difference of playing American League teams on the road," LaRoche said of the quick swings in momentum. "It's tough."

The morale wouldn't get any better in the trip to Chicago. On Tuesday, an early lead and a fifth-inning tie eventually morphed into an 11-run loss. One day later, another manageable deficit got out of hand late.

The Pirates held leads in five of the six games, with four of those leads being of at least two runs. Regardless, they resulted in only one win.

"I think it's deflating, losing five out of six, anyway you lose them," said Nate McLouth.

Still, Thursday's loss may have been the most crushing.

Everything started out perfectly, with the Pirates bursting out of the gate with a six-run second against Chicago starter Gavin Floyd.

Taking advantage of a throwing error by Chicago third baseman Pablo Ozuna, the Pirates dented the scoreboard first. Nate McLouth followed with a bases-clearing double, before Freddy Sanchez knocked a two-run homer.

Dumatrait had a seemingly commanding 6-0 lead. However, it wouldn't last long.

"It seemed like everything else I was throwing up there, they were hitting," said Dumatrait (3-4). "It didn't help, either, that some of the pitches were up in the zone. Obviously they bit me there."

He gave up consecutive doubles to start the second inning, before three of the next four Chicago hitters found holes, to cut the Bucs' lead in half. Chicago shortstop Orlando Cabrera then finished erasing the deficit with a three-run homer.

"For them to come back and watch them drop six on us, just like that, was tough," said McLouth, who finished with three runs scored and three RBIs in the game. "We had a lot of momentum there."

Added LaRoche: "Those are the quickest 12 runs I've ever seen scored."

From there, the two teams traded runs over the next two frames, with the Pirates' seventh run of the afternoon coming on another RBI hit from Sanchez.

But Dumatrait couldn't hold that lead either, giving up runs in both the fifth and sixth. In all, Dumatrait stayed in to finish five innings. He'd be charged with 11 hits and nine runs, marking his worst start of the season in terms of both hits and runs allowed.

Neither he nor manager John Russell, though, attributed the drubbing to Dumatrait missing something from his repertoire. It was more of a case of the White Sox just not missing a beat, they said.

"I felt good," Dumatrait said. "They were just hitting everything."

Chicago outfielder Jermaine Dye then poured salt in the wound with a seventh-inning grand slam off reliever John Grabow to give Dye two homers Thursday, and Chicago 10 home runs this series.

In all, the Pirates would be outscored, 13-2, to finish the game.

"They're obviously swinging the bat very well," Russell said. "They all seem to be clicking together. There's not much else you can say."

The varying highs and lows of the starting rotation hit a deep valley on this two-city road swing. The starters had just one quality start in all (Paul Maholm: two runs in six innings) and finished with an ERA of 8.72. Half of the starts made on this trip didn't even last until the sixth inning.

With the loss, the Pirates are now 1-8 in the Windy City this season, and they now return home for nine more games against A.L. teams.

"We've almost got to act like it didn't even happen and just start over," LaRoche said. "There's obviously no momentum right now, and we've got to find a way to pull our team back together."