HOUSTON -- The San Diego Padres needed one big inning on Saturday night to shake out of their recent offensive doldrums.
San Diego had reached six runs only once since July 27 and lost nine of 13 games. Cameron said Walker's leadoff homer in the four-run fourth loosened up a tense San Diego dugout.
"It got us off the snide," said Cameron. "It was good for the whole team. We've been scuffling a little bit. It was a good thing for us to just go out and break the ice a little bit."
Later in the inning, Barfield added a solo shot and Cameron hit a two-run shot that gave Padres starter Jake Peavy (6-11) all the support he needed.
Peavy struck out nine in seven strong innings, earning only his second win since May 28.
"Hopefully, that will get the boys rolling and get everybody relaxed a little bit," Peavy said. "That inning was huge."
Hirsh, promoted from Triple-A Round Rock earlier in the day, was rocked in his major league debut. He had given up just five home runs all season in 23 starts in the minors.
"I just wasn't as sharp as I hoped I would be," said Hirsh. "I was missing in and up and down. Obviously, some of those balls were hit pretty well."
Trevor Hoffman pitched a perfect ninth to get his 31st save in his 35th chance.
"We did a little bit of everything tonight, which was good for the whole team," Cameron said. "When we're playing good, that's the way we play."
Until Berkman's homer, Peavy had the Astros baffled, striking out seven of 11 batters he faced between the second and fifth innings.
Peavy has been dealing with tendinitis in his throwing shoulder, but says he's finally healthy.
"I felt a lot better than I have all year," said Peavy, who threw 111 pitches. "I feel like fatigue's not a factor, feel like I'm not going to hurt myself being out there."
Hirsh's first outing, meanwhile, quickly fell apart after a solid first three innings.
Walker hit Hirsh's first pitch of the fourth into the upper deck in right field and with one out, Barfield sent the first pitch into the left-field seats. Dave Roberts singled with two outs and Cameron then connected for his 16th home run.
Padres manager Bruce Bochy complimented his players for being aggressive at the plate, swinging early in pitch counts.
"They looked like they got after it better," Bochy said. "You've got to play this game free and easy. It looked like we've tightened up a little bit."
Russ Springer relieved Hirsh starting the fifth. The Astros had been eager to recall the 6-foot-8 Hirsh, who was 13-2 with a 2.10 ERA in the minors and led the Pacific Coast League with 118 strikeouts.
"He was keyed up, may have had a little bit of anxiety," said Houston manager Phil Garner. "But he didn't seem overly nervous to me."
Peavy retired eight straight Astros after Adam Everett's infield single in the second inning. Everett reached on an error leading off the fifth, but Peavy fanned Brad Ausmus for the second time, got pinch-hitter Orlando Palmeiro on a ground out and struck out Willy Taveras.
Peavy walked Craig Biggio leading off the sixth and Berkman followed with an opposite-field home run that barely cleared the left-field wall. Berkman has hit 27 of his 32 homers batting left-handed.
- The Padres hit three homers in the same inning for the first time since a 7-5 win over Kansas City on July 2, 2004.
- Taveras singled in the first inning to extend his career-best hitting streak to 15 games.
- Hirsh was the sixth rookie pitcher the Astros have used this season.
- Before the game, the Astros honored former play-by-play man Gene Elston, the 2006 recipient of the Ford C. Frick Award. The 84-year-old Elston was the franchise's first radio announcer and worked in Houston from 1962-86 during his 47-year broadcasting career.