The 24-year-old left-hander dominated the D-backs throughout the game, pitching eight-plus innings while giving up one unearned run on two hits.
"You're just hoping you can hang in there and get to a guy like Bumgarner," manager Kirk Gibson said. "He was exceptional. This may be the best I've ever seen him."
Bumgarner ran through the D-backs' lineup through the first eight innings, allowing only three baserunners. The only hit he allowed before the ninth was a slow roller off the bat of Cody Ross, and Ross barely beat the throw to first.
Despite his performance, Bumgarner was complimentary of the D-backs.
"They're a good team," Bumgarner said. "I feel like it's always a battle coming in playing them."
Fortunately for the D-backs, their pitcher went toe to toe with Bumgarner.
Rookie Mike Bolsinger, making his second start since being recalled from Triple-A Reno, had the best outing of his short Major League career.
The 26-year-old right-hander, who came into the game with a 5.70 ERA in six big league games, went a career-best 7 2/3 innings while giving up only one run on five hits and striking out four. He threw 69 percent of his pitches for strikes and kept Giants hitters off balance.
"I came up, had a little success, went down and now I'm coming back," Bolsinger said. "I just want to keep rolling with it."
Bolsinger's only rough inning came in the fifth when he walked shortstop Brandon Crawford and gave up an RBI double to left fielder Tyler Colvin. But other than the sole run, Bolsinger excelled.
"He made a bad pitch to Colvin," Gibson said. "Other than that, he pitched really good."
But the D-backs' offense and bullpen didn't equal Bolsinger's effort.
After Bolsinger left the game, Gibson brought in Oliver Perez, who got out of the eighth inning. The next two relievers were not as successful.
Evan Marshall started the ninth, but he gave up a single to right fielder Hunter Pence and a run-scoring double to catcher Buster Posey, ending his short outing.
The next reliever, Joe Thatcher, didn't do much better, giving up a single to Crawford and a double to rookie second baseman Joe Panik and allowing the Giants to stretch their lead to 4-0.
Meanwhile, the anemic offense didn't get a second hit until the ninth inning. It did manage to get the tying run to the plate in the best possible situation -- Paul Goldschmidt at the plate with two runners on -- but Giants closer Sergio Romo got Goldschmidt to hit into a double play to effectively end the threat.
"We finally were able to break through a little bit against them that last inning, get two guys on," Goldschmidt said. "But Romo came in and did a good job for them."