This time, he's trying to lead them to highest win total in nine years.
Bumgarner makes his final start of the regular season Saturday night, when he goes for a fifth consecutive win against the Padres.
Bumgarner (16-10, 3.26 ERA) is 4-0 with a 2.66 ERA in his last six starts against San Diego (74-83), and all of them have resulted in wins for San Francisco (92-65).
The 23-year-old left-hander's most important victory over his division rival may have come last Saturday, when he yielded three runs with six strikeouts in 5 2-3 innings of an 8-4 home victory. It clinched the Giants' second West title in three seasons and gave Bumgarner wins in back-to-back outings after going 0-3 with a 7.29 ERA.
Bumgarner will now try to give the Giants their most wins in a season since getting 95 in 2002. He's also trying to become the franchise's first southpaw to win 17 games since Shawn Estes managed 19 in 1997.
San Francisco looks to keep rolling into the postseason, it's won 13 of 16 while averaging 5.4 runs and hitting .309. That type of production tends to be more than enough with Bumgarner on the mound.
He's 31-3 when he gets at least three runs of support.
The Giants' offensive barrage continued with 10 hits, including a pair of doubles and triples, in Friday's 3-1 win over the Padres in the opener of this three-game set at Petco Park.
Buster Posey is 6 for 15 with two doubles and a triple in four games, as he continues to pull further ahead in the NL batting race. The catcher survived a scary moment after taking a wild pitch in the throat thrown by Ryan Vogelsong.
"When I got there, I could see the seam mark on his Adam's apple, so I knew it got him good,'' Vogelsong said. ''I know he is a tough son of a gun. I think if I got hit in the throat while I was catching, I'd probably be laying on the training table.''
Posey is hitting a career-high .334, four points ahead of Pittsburgh's Andrew McCutchen heading into the final five games of the regular season.
The two are vying for the batting title since San Francisco's Melky Cabrera, hitting .346, won't qualify at his own request after a positive drug test. Posey, who had a double and a triple Friday, is bidding to become the first catcher to win the NL batting crown since Hall of Famer Ernie Lombardi did it with the Boston Braves in 1942.
The Padres have been outscored 19-7 during a three-game slide and will turn to Eric Stults (7-3, 2.81) to end the losing streak.
The left-hander is 6-1 with a 2.60 ERA over his last nine starts, including Sunday's 6-4 win over the Giants. He allowed three runs and seven hits in six innings, beating them for the first time since a start with the Los Angeles Dodgers on May 9, 2009.
"That was fairly typical of what Eric has given us," manager Bud Black said. "A wide range of velocities and a mix of pitches."
Stults wasn't nearly that sharp at home against San Francisco on Aug. 18, giving up five runs and nine hits in six innings while not getting a decision in an 8-7 defeat.
Posey is 2 for 4 with a double off him.