SAN DIEGO -- The Pirates are headed back to Pittsburgh with a patchwork pitching rotation and a couple of green rookie relievers suddenly thrust into prominence.

The Pirates also are returning home with a boost in confidence after a winning road trip. They closed their stretch of 11 games in 11 days across three cities with a 6-4 victory over the Padres at Petco Park on Sunday afternoon.

Pittsburgh finished its swing through St. Louis, Arizona and San Diego with seven wins in those 11 games. The Bucs also ascended into the second spot in the National League Wild Card standings with a 24-20 record, a half-game ahead of the D-backs and Braves.

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“It was a very strong finish,” said manager Clint Hurdle, whose club won the final three games of a four-game set at San Diego. “I’m proud of the effort. I’m proud of the energy, and the offense is starting to do some things that are significant, as well. It was a fun trip for us. It was a good baseball trip.”

Josh Bell had an RBI single and Colin Moran drilled a three-run home run off rookie Cal Quantrill in the first inning as the Pirates staked right-hander Joe Musgrove to a 4-0 lead before he threw a pitch. The four-run first matched the Bucs’ best first inning of the season. They also scored four against San Francisco’s Madison Bumgarner on April 19. Unlike that game, a 4-1 victory, the offense added on this time around.

Melky Cabrera made it 5-0 with an RBI single in the fifth, his 1,900th career hit. Moran collected his fourth RBI of the day on a single in the eighth after the Padres scored four times in the seventh to make a game of it. It was the second straight day that the Pirates opened a big lead and held on for victory.

“Offensively, we’ve got a lot of talent in the lineup,” Moran said. “It was just a matter of time before we were clicking all the way through."

For six innings, it appeared the Bucs’ first run -- courtesy of Bell’s 44th RBI of the season -- would be all that Musgrove needed. Musgrove, who grew up in suburban San Diego and was pitching at Petco Park for the second time in his career, allowed only one hit and one walk through the first six, and he erased each of those runners; one with a pickoff and the other with a double-play grounder.

The third time through the order proved more challenging as the Padres scored four runs off Musgrove in the seventh, three on Hunter Renfroe’s home run to center. But the Pirates still held a 5-4 lead at that point, and rookie Geoff Hartlieb came in to record two outs to get out of the inning and put the game in the capable hands of Francisco Liriano, who pitched a scoreless eighth, and Felipe Vazquez, who worked a scoreless ninth for his 13th save.

“I felt really good today,” Musgrove said. “It’s probably the best I’ve felt in terms of pitch-sequencing and execution, mentality -- everything was there. It’s unfortunate I let things get away from me in that last inning, but I was still making pitches. Overall, I felt like I threw the ball well."

To use Hartlieb with a one-run lead, Hurdle showed that he liked what he saw Saturday, when the right-hander threw 95 to 98 mph in his Major League debut, finishing off a Bucs victory. Fellow rookie Montana DuRapau served as the opener in that game, showing good stuff for two innings.

The opener strategy remains in play for the Pirates, who can count on only Musgrove and Jordan Lyles as healthy and reliable starting pitchers. The rotation lost Trevor Williams to a right side strain Thursday, and Chris Archer has yet to regain form after his IL stint because of right thumb inflammation.

Whoever fills the open spots in the rotation moving forward, the challenge will be easier if Pittsburgh hits like it did this weekend.

“Our energy is really good right now,” Musgrove said. “Our young guys have been tough, amazing. Everybody is clicking on all cylinders right now. With us missing so many guys right now, everyone has done a good job of picking each other up and supporting each other.

“It might sound cheesy, but the love from your teammates and the confidence you get from the guys in this clubhouse is really pushing this team in the right direction."