PITTSBURGH -- Ozzie Guillen is usually quick to give an answer for any question.

But even Guillen was left speechless as to why the Marlins keep coming up short.

“I don’t know what to say anymore,” Guillen said. “I was thinking during the game what do I tell the media when they ask why we lost. I’ve said everything I could say already.”

Pitcher Anibal Sanchez gave the Marlins a quality start, but more offensive futility wasted the effort in a 3-0 loss that completed a three-game sweep for the host Pirates in front of a crowd of 34,203.

Sanchez went seven innings and struck out eight, but he couldn’t prevent the Marlins’ fifth consecutive defeat that moved them to a season-worst seven games under .500.

Pirates pitcher Jeff Karstens gave up five hits and two walks in seven scoreless innings, combining with Jared Hughes and Joel Hanrahan (28th save) for the shutout, which was the Marlins’ 10th this season and seventh on the road.

The Marlins (44-51) finished the road trip with a 1-5 record and have scored seven runs during the losing streak.

“This stretch has been terrible,” catcher Brett Hayes said. “We’ve been playing like crap. It seems like nothing is going well right now. We’re not going to give up. The effort is there. We’re playing hard, but for whatever reason it’s always something.”

For Sanchez, it could have been his final such performance in a Marlins uniform.

The 28-year-old right-hander, who fell to 5-7 with a 3.94 ERA for the season, has been mentioned as a potential trade piece before the July 31 trade deadline.

“I don’t have a problem with that,” Sanchez said. “At this time of year, it is the trade times. I’m going to be a free agent at the end of the year. But it’s not like I feel pressure because of it.”

According to an online blog post by Fox Sports, Sanchez was being scouted Sunday by the Tigers and the Red Sox, the team that drafted him. Sanchez is scheduled to make one more start before the deadline, July 28 at home against the Padres.

“Whether they trade me or not, I will always be grateful to this team,” Sanchez said. “They have always treated me really well. I can only control what I can control. I will go to the stadium [Monday] early like I always do and start preparing for my next start. I think the team has a lot of responsibilities, and it’s a hard position for them to be in right now.”

Sanchez gave up a run in the first inning when National League batting leader Andrew McCutchen lined a single to center field to score Alex Presley.

But Sanchez was sharp after that, retiring 12 batters from the end of the second inning to the sixth when McCutchen singled again with two outs.

The crushing blow for Sanchez and the Marlins came in the bottom of the seventh when following a Casey McGehee double, third baseman Pedro Alvarez smacked a breaking ball over the right-center-field fence.

“I just made a mistake in the seventh inning and cost us two runs,” Sanchez said. “He waited for the pitch, and it was one I didn’t throw the whole game. I tried to get a ground ball out of it, but he hit it good, and I paid for it.”

The Marlins once again squandered chances at the plate to support Sanchez.