SAN DIEGO -- A rare big night from the Padres' offense overshadowed Tim Stauffer stepping into the depleted rotation and giving San Diego a strong start.
"That was a great lift for the staff," Padres manager Bud Black said.
The Padres set a season-high in runs and had 12 hits. Everyone but Will Venable had at least one hit among the starting position players.
Making his first start since May 14, 2012 at Washington, Stauffer pitched five shutout innings and gave up two hits.
"And two years from now it should feel pretty good again," Stauffer joked about his time between starts.
"It felt good and after getting through that first inning, the offense really set the tone. After that I was just trying to keep pitches down and eat up some innings and keep the bullpen fresh."
Stauffer struck out five, with a walk and hit batter and earned his win as a starter win since Sept. 16, 2011, against Arizona.
The Padres snapped a four-game losing streak with a performance which was out-of-character for a team which has been shut out eight times, tops in the majors.
"We haven't had many of those games," Black said. "A couple, but not many. When that happens there is a different feeling in the dugout and a different vibe. Everyone wants to get to the bat rack, to start hacking and wanting to get involved."
Edwin Jackson (3-4) took the loss, allowing eight runs and nine hits in just four innings.
The Cubs managed one runner in scoring position through six innings before Welington Castillo drove in Luis Valbuena with a broken-bat single in the seventh. Three relievers completed the five-hitter for San Diego.
The Padres scored four first-inning runs, matching their total from the previous three games.
Seth Smith drove in two with a single and after Headley reached on a fielder's choice, Alonso smacked his second home run of the season. The Padres began Friday averaging 2.98 runs per game, the lowest in the majors.
Grandal opened the second inning with his fifth homer, this one to the opposite field. Everth Cabrera and Cameron Maybin singled and Headley brought them home with a booming double to right for a 7-0 cushion.
"It's about time," Grandal said. "I've been hitting fly balls that way and they all seem to be short. I was lucky enough to hit one that actually carried a little bit more."
Headley added his third RBI with a fourth-inning single after Maybin doubled.
All of this came at the expense of Jackson, a pitcher the Padres flirted with before he signed last year as a free agent with the Cubs. He's now 0-5 against the Padres, with a 6.94 ERA.
Jackson had been keen avoiding the long ball -- only two home runs allowed in this season's previous nine starts. But he's had trouble in the early innings and that rang true against the Padres.
Of Jackson's 31 earned runs this year, 23 have come in the first two innings.
"His command wasn't as sharp as it has been," Cubs manager Rick Renteria said.
Cabrera, Maybin, Alonso, Headley and Jedd Gyorko each had two hits for the Padres.
"The swung the bats well and took advantage of Jackson," Renteria said.
The Padres juggled their rotation with LHP Robbie Erlin joining RHP Andrew Cashner (elbow) on the DL this week with elbow soreness. Donn Roach was bumped from Saturday's start, with Billy Buckner expected to fill in after being promoted from Triple-A El Paso. That made Roach available for relief on Friday; he worked a scoreless inning. Buckner, who was signed April 19, was 3-2 with a 2.98 in five starts at El Paso. . OF Carlos Quentin, who last played on Sunday when straining his groin, is available for pinch hitting. . Cubs OF Justin Ruggiano played in his second straight game at Triple-A Iowa; he's been on the DL since April 24 with a strained hamstring. . RHP Pedro Strop (groin strain) is close to making a rehabilitation start. . Cubs LHP Travis Wood (4-4, 4.61) faces Padres RHP Billy Buckner (0-0, 0.00) on Saturday night.