OAKLAND, Calif. -- The Oakland Athletics appear to be coming out of their season-long offensive slump.

A day after pounding out 13 hits and scoring a season-high 12 runs, the A's took advantage of a Kansas City fielding error to score five runs in the seventh inning on the way to a 7-2 win over the Royals on Wednesday night.

"It's just a matter of time," said Oakland designated hitter Jack Cust, whose three-run double broke open a close game and helped Josh Outman win his first game of the season. "Guys have been swinging the bats better and doing the little things ... trying to push across runs any way we can instead of waiting for the home run or the big hit."

The A's went into the series ranked last in the AL in multiple offensive categories, but pounded out 20 runs and 20 hits in the two games against Kansas City.

Adam Kennedy went 2-for-3 with a double, his first multi-hit game since being acquired in a minor league trade from Tampa Bay last week. Orlando Cabrera, who had three hits and four RBIs in the A's 12-3 win on Tuesday, scored twice from the leadoff spot while Kurt Suzuki also scored twice.

"Everybody's contributing up and down the lineup," Oakland manager Bob Geren said. "Every inning we feel like we can score. It's a good feeling. When they get pitches, they're not missing them."

Kansas City starter Brian Bannister (3-1) gave up two runs in 5 2/3 innings and lost for the first time this season. The right-hander left the game with tightness in his right shoulder after Cust hit a sacrifice fly in the sixth.

"It was the right move," Bannister said of the decision to pull him. "This has happened a couple of times in my career where I've had mild tendinitis and I've dealt with it. I just throw a little less between starts. I was having trouble getting on top of my pitches. I was throwing well to that point."

Outman (1-0) was stellar in his best outing of the season. The right-hander allowed just three hits and a run in six innings to get his first win in five starts while helping the A's complete the two-game sweep. Outman retired the side in order four times, walked two and struck out four. He allowed only Miguel Olivo's RBI-single in the second before giving way to the bullpen.

"Throwing strikes, that was the biggest difference," Outman said. "I hadn't been around the strike zone. We had to get back in the strike zone and just prove to myself that when I'm in the strike zone consistently like that, attacking hitters and making them stay defensive, I can pitch deep into games and can compete with anyone."

Michael Wuertz, Russ Springer and Andrew Bailey completed the four-hitter for the A's.

Mike Jacobs homered for the Royals, who went winless on their five-game road trip after winning six straight at home. It's the first time since 2006 that Kansas City has been swept on a road trip of five games or more.

"We have to find runs," Royals manager Trey Hillman said. "We have to streak it up on the upside soon. For five days we didn't swing the bats as consistently well as I know we can. We also had a lack of two-out hits. We need to right the ship when we get back home."

Oakland broke the game open with five unearned runs in the seventh, three coming on Cust's double off reliever Jamey Wright after a fielding error by Kansas City third baseman Mark Teahen helped extend the inning.

Bannister had allowed more than one earned run just once in his previous four starts and sailed through the first five innings against Oakland before running into trouble in the sixth. He gave up three straight one-out hits then walked Matt Holliday before Cust's sacrifice fly gave the A's a 2-1 lead.

Hillman and trainer Nick Swartz met briefly with Bannister on the mound after the play before Hillman called for reliever Horacio Ramirez.

Bailey allowed a solo home run to Jacobs in the ninth. Bailey had retired 16 straight batters working out of the bullpen before the homer.

Game notes
Cust has driven in four runs in a game seven times in his career. ... Oakland C Kurt Suzuki went 1-for-3 and is batting .378 (28 for 74) with 10 doubles and 15 RBIs over his last 19 games. ... Olivo extended his hitting streak to eight games with his RBI-single in the second.