Berkman and Kent hit leadoff shots in the second and fourth innings, respectively, before Ensberg made it 3-0 with two outs in the fifth.
(4-0) earned the win with 1 2/3 scoreless innings in relief, allowing two hits.
"Different people contributed," Astros manager
said. "We got some big hits late to add on some runs."
was pulled after just 3 2/3 innings. While he did not allow a run, he struggled with his control, walking four and throwing just 43-of-89 pitches for strikes.
"It was a manager's decision to take Linebrink out, he had thrown a lot of pitches," Williams said. "He had good stuff, he was just outside the strike zone. We need to have our starters go deeper, pitch effectively later into the game."
"It was just from early on," Linebrink added. "I couldn't control the fastball. For me, everything works off the fastball. If I'm not getting that over, I have to go to my other pitches. I was having trouble getting them over, too. When you give up four walks, you open it up."
, who was recalled from Class AAA New Orleans earlier in the day, took over for Linebrink and allowed one run and four hits in 1 2/3 innings.
"I got up at 5 this morning," Robertson said. "Definitely a long day that ended up well."
The contest drew just 9,095 on a rainy and chilly night, the first crowd under 10,000 in the three-year history of PNC Park.
"Without our bullpen doing a great job this year, we would be in serious trouble," said Astros center fielder
, who had three hits. "They came in tonight, they did a great job. It was a nasty night. We battled, got some runs late."
The Pirates got back a run on
's RBI single in the fifth, then loaded the bases with one out in the sixth. But Stone took over for Robertson and gave up only a sacrifice fly to
The Pirates had their chances, stranding 12 runners. In the first six innings, they were 1-for-14 with runners in scoring position.
Houston got some breathing room in the eighth when two runs scored on shortstop
's throwing error, then broke open the game with four runs in the ninth. Berkman delivered a two-run single in the inning and two runs scored on wild pitches by
(2-1) took the loss, giving up all three homers and allowing six hits in five innings.
"This was one of those games where nothing seemed to go our way," Torres said. "Today, I just couldn't get my fastball down. I knew where I wanted to throw it but I couldn't find a way to keep the ball down."
The Pirates have dropped nine of their last 10 games and fell to just 5-14 at PNC Park. They also have lost nine straight to Houston.
"We have to get out of the funk we're in," Pirates right fielder
said. "Even though we know the things that are going on, it's just a matter of getting the team turned around. The team's taking extra batting practice, fielding extra ground balls. Right now, whatever we try, it's just not working."
singled in the bottom of the sixth, extending his hitting streak to 12 games.