PHOENIX -- Diamondbacks manager Kirk Gibson is looking for a strong finish heading into the postseason.

Sure looked pretty good Saturday night.

Ian Kennedy pitched six innings to earn his NL-best 21st win and Arizona routed the San Francisco Giants 15-2, eliminating the defending World Series champions from the postseason picture.

"We played good today, we played very loose," Gibson said. "You got out in the first inning like that, having Ian on the mound settle things down, pitched well, got to play everybody, pitched a lot of guys and managed (Kennedy's) pitch count."

Gerardo Parra had two hits and four RBI for the Diamondbacks, who scored six times in the first and equaled their highest scoring game of the season. Ryan Roberts drove in three runs.

Arizona also matched a franchise record with 13 walks one night after it beat San Francisco 3-1 to clinch the NL West title. The Diamondbacks also had 13 walks in a 5-4, 13-inning victory against Houston on June 5, 2002.

The 13 walks also tied a San Francisco record, accomplished three times previously.

"It was an ugly game," Giants manager Bruce Bochy said. "It started out bad and got worse. We walked 13 hitters, and that should not happen."

San Francisco was eliminated from the wild-card race with the loss. The Giants fell behind Arizona when they lost to Pittsburgh on Aug. 10 and never regained first place in the division.

Kennedy (21-4) allowed two runs and five hits, struck out four and walked two. The right-hander is 6-0 with a 1.66 ERA in his last seven starts.

The Diamondbacks remained one game back of Milwaukee for the second-best record in the National League, with home-field advantage for the first round of the playoffs at stake.

"We want to go out there and give 100 percent and we don't want to give any games away and tonight was no different," Roberts said.

Arizona jumped out to a quick lead against Eric Surkamp (2-1), who walked four and recorded just two outs. Roberts and Parra each had a two-run single, and Kennedy capped the big first inning with a two-run double.

The Giants experienced some bad luck on Parra's hit, with second baseman Mike Fontenot running into second base umpire Bruce Dreckman. The collision allowed the routine grounder to go into center field, scoring Paul Goldschmidt and Roberts.

The Diamondbacks added five more runs in the sixth, and the rout was on. Roberts had another run-scoring single, lumbering catcher Henry Blanco tripled home a run and pinch-hitter Sean Burroughs added an RBI single for an 11-2 lead.

Pablo Sandoval had two RBI for San Francisco, which allowed a season high for runs.

The Diamondbacks improved to 92-66, tying for the third-most victories in franchise history. They won 100 in 1999 and 96 in 2002.

Notes

• With the Diamondbacks batting in the bottom of the seventh, Chase Field experienced a power failure. Play resumed after a delay of 27 minutes.
• Gibson announced starter Jarrod Parker, the team's top draft pick in 2007, will make his major league debut Tuesday against the Dodgers.
• Blanco's triple was the 11th of his career and his first since Sept. 10, 2006, with the Chicago Cubs.
• When the Giants return home Monday, they will set an single-season franchise attendance record. In 2011, they sold 3,261,104 tickets, and will sell out every game.
• Tim Lincecum (13-13, 2.59 ERA) will start for the Giants on Sunday, and Josh Collmenter (9-10, 3.42) will pitch for Arizona.
• The crowd of 49,076 was the third sellout of the season for the Diamondbacks.