PHOENIX -- Whether he will acknowledge this fact or not, pitcher Ian Kennedy is very often at the mercy of his lineup and bullpen. When each is doing its part, Kennedy can pitch well and win: Monday against the Mets, he allowed one run in five frames and the D-backs kicked off a three-game winning streak.

On the other hand, when the lineup is scuffling and the bullpen bungles, Kennedy can pitch well and lose: Saturday opposing the Giants, he allowed three runs in 6 2/3 innings but was charged with a fourth (thanks to the poor 'pen) to cement Arizona's three-game losing streak.

Batters one through eight also didn't support their starter in the club's 10-4 defeat Saturday, its sixth straight loss to San Francisco. In fact, Arizona has done little damage since Thursday -- when Matt Cain began the Giants' roll -- having gone 2-for-24 with runners in scoring position and plated just eight runs.

Add to that this: The D-backs still have to deal with two-time Cy Young Award winner Tim Lincecum, who closes out the series Sunday against Barry Enright.

"It's a brutal game sometimes, and we have to try and push through it," said interim skipper Kirk Gibson, holding out hope for a 4-3 record the past week at Chase Field. "We have a tough task with Lincecum tomorrow. We'll try to get one out of this [series] and have a [winning] homestand. It could have been better."

To best Bumgarner on Saturday, Kennedy (5-8) needed to be perfect. Or close to it.

He avoided the big inning but also let the Giants chip away. In the first, Edgar Renteria doubled, advanced to third base on a Kennedy wild pitch and scored on Aubrey Huff's fielder's choice. San Francisco added on in the fifth: Bumgarner (walk) advanced to third base on Andres Torres' double and scored on Renteria's fielder's choice. Torres came home two batters later on Buster Posey's RBI single.

After Kennedy's exit with two outs in the seventh, lefty Jordan Norberto allowed a Huff single and righty Sam Demel walked Posey ahead of Juan Uribe's grand slam over the left-field fence.

"We tried to match up against Huff," Gibson said of the Giants' first baseman, who homered twice Friday. "He's swinging the bat really good, probably as good as I've ever seen him. He cheated on the fastball yesterday on Edwin [Jackson] on the home run, and he did on Norbie. I give him credit there."

Former closer Chad Qualls (8.49 ERA) replaced Demel in the seventh but yielded three runs in two-thirds of an inning before Aaron Heilman quieted things down.

Offense on the other side was silent most of the night thanks to you-know-who. Bumgarner, who was selected one spot (No. 10 overall) after the D-backs picked Jarrod Parker in the 2007 First-Year Player Draft, yielded only Mark Reynolds' sixth-inning solo home run, his 23rd, and Tony Abreu's seventh-inning sacrifice fly. The left-hander struck out a career-high seven.

"He was throwing all his pitches for strikes," Reynolds said. "He had a little sidearm action going, and some of his pitches were tough to pull the trigger on."

"Really, I had three pitches going pretty good," Bumgarner confirmed. "I had the curveball working better later on and the slider was working the whole game and the fastball, too."

It took Bumgarner's exit for Arizona to manicure its box-score totals: Adam LaRoche's two-run homer off Guillermo Mota in the eighth caused some excitement but had no bearing on the game.

No, to stay in Saturday's game and afford Kennedy his first three-game winning streak of the season, the D-backs would have needed to capitalize on situations like the first and fourth innings, when Chris Young and Justin Upton, respectively, smacked leadoff doubles.

"We're in fix-it mode," admitted LaRoche, who struck out twice against Bumgarner before his late-inning blast off Mota. "We need to relax and not put so much pressure on every at-bat and every pitch."