PITTSBURGH -- Considering how the Astros have been performing lately, it was probably a little optimistic to think they'd have any better luck against a pitcher with an 18.90 ERA this year.
Instead of taking a golden opportunity and running with it, the Astros instead bowed meekly to Tony Armas and the Pittsburgh Pirates, dropping a 5-3 decision before 12,056 at PNC Park and extending their season-high losing streak to six games.

Less than a week after winning five in a row, the Astros find themselves unable to do anything particularly well, except leave men on base. They stranded 13 more on Thursday to bring their grand total from the three-game series to 36, dropping to 0-6 on the year against the Pirates, who have only four wins against clubs other than the Astros.

"Goodness gracious alive, to lose six to anybody ... " manager Phil Garner said. "The frustrating thing is they've not played well, either. They played well in the first three games against us and did not play well until they faced us again. They hadn't won a game [at PNC Park] until we got here. They hadn't pitched well. The bullpen's done a good job. But this kid today had struggled a little bit. We just didn't come up with the big hit when we needed it."

Armas entered this game having allowed 14 earned runs over 6 2/3 innings, spanning two very disappointing starts. He wasn't particularly efficient against the Astros, throwing 113 pitches over five innings, but the Astros continued to let him off the hook.

Things looked good early. Chris Burke led off with a double, moved to third on Mark Loretta's infield single and scored on Lance Berkman's sacrifice fly.

But the Astros did not score again during Armas' five-plus inning performance and only sprung to life in the ninth, when it was too late.

In between, the Astros produced 12 baserunners. None scored.

"Another day with a lot of people left on base," Garner said. "Still have trouble coming up with the big hit. We started off in the first inning and it looked like it was going to be a big day for us -- couple of hits, it looked like we were getting going, then a double play a couple of times took us out of the inning. We just didn't get it going, obviously."

Carlos Lee was responsible for six stranded baserunners and acknowledged later that the Astros should have done more against Armas.

"It's tough because when you have a guy that is a dominant pitcher, you say he was on his game and he pitched good and all that," Lee said. "But we didn't get the big hit, that's all. It seems like that's been happening the last three days. It seems like it's late before we get it going. There's nothing we can do about it. We'll just go home and try to turn it around."

The sputtering offense negated what was arguably Wandy Rodriguez's best start of the year. The left-hander held the Bucs to two runs over seven-plus frames in a 101-pitch outing, tying his career high with seven strikeouts.

Rodriguez held the Pirates scoreless until the sixth, when he yielded a two-run single to Jason Bay.

"Wandy pitched beautifully today," Garner said. "I thought two calls went against us that hurt and that's going to happen. It seems like it happens when you're struggling. I thought he had [Chris] Duffy struck out [in the sixth]. He pitched a real good game."

Garner also disagreed with first-base umpire Sam Holbrook's call on a Freddy Sanchez ground ball. Mike Lamb's throw appeared to get to Berkman in plenty of time, but Sanchez was called safe.

Rodriguez, still looking for his first win since last July, focused on the positives of this outing.

"The difference between the last game and this game was the last game, I missed a lot of spots," Rodriguez said. "But this game, I hit the spots. I took advantage of the experience of the last game to this game, and I was able to hit the spots where I wanted to."

The Astros finished their four-city, nine-game trek with a 3-6 record, after starting 3-0 with two wins in Cincinnati and one in Milwaukee.

"The games in Milwaukee, they were good games," Lee said. "We battled, we played good, we faced tough pitching. We lost two of three but played good. We went to Philly and things started getting ugly. We couldn't get anything going. And these three games [in Pittsburgh] were terrible."

"It's good to be going home," Garner said. "But [the extended road trip is] no excuse. We're in good shape. Our pitching staff's in good shape, and they pitched pretty decently. We just lost our offense. We couldn't get anything going. But we've had some good games in this stretch, and we've had some games that we just didn't appear to be focused. It'll be a good time to go home and get something started."

Alyson Footer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.