OAKLAND, Calif. -- After the way Cubs right-hander Jake Arrieta finished last season en route to winning the National League Cy Young Award and started this season, he was overdue for a rough streak.

Arrieta went 11-0 with a 0.57 ERA over his final 13 regular-season starts last year, and the Cubs went 13-0 during that stretch. This year, he went 9-0 with a 1.72 ERA in his first 10 starts as the Cubs won all 10.

But over his past five starts, Arrieta has gone 0-3 with a 4.88 ERA, and the Cubs have lost all five games. He'll try to end that skid Saturday afternoon against the Oakland A's in the second game of a three-game series at the Oakland Coliseum.

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"I just think we all (have) high highs and lows," catcher David Ross said Friday before the Cubs' 7-2 victory against Oakland. "It's going to be hard to sustain what he was doing. I don't think anything's wrong.

"I think we all went through a little stretch there where we were kind of fatigued. I think the All-Star break helped him recover and he's pitched well since then. It could be fatigue, it could be rhythm, it could be any number of things. But for how long he sustained just being completely unhittable, I think everybody said, 'What's wrong?' when he gives up a couple runs."

Arrieta (12-5) certainly isn't sweating his mini-slump. In his previous start, he gave up two runs on two hits over seven innings in a 4-1 loss to Seattle. Two starts before that, he held the Mets to one run on five hits over seven innings and got a no-decision in a 2-1 loss.

"Yeah, two hits," Arrieta said of his start against the Mariners. "Two walks in the 8th or it could have easily been a different story. A couple close calls led to a couple base runners. They ended up getting a couple.

"Sometimes this game does weird things to you. But trying to get locked in and be at our best individually down the stretch is the most important thing for us. That's kind of what we're striving to do."

Oakland catcher Stephen Vogt said the A's are expecting nothing but the best from Arrieta.

"I faced him a lot in the minor leagues," Vogt said. "You can't say enough about what he's done over the last couple years. It's pretty special. I'm looking forward to the challenge. He's got some of the best numbers in baseball and he's had some of the best success over the last couple years. It will be a good challenge for us. I'm looking forward to it."

A's right-hander Sonny Gray will be looking again to recapture the command he had last year when he finished third in the American League Cy Young Award voting. Gray is 5-10 with a 5.84 ERA and 15 wild pitches.

"Obviously he's frustrated and obviously he's working to get better every day," Vogt said. "It's just been kind of when he hasn't been good, they take advantage of him, and when he has been good, bounces haven't gone his way.

"So it's kind of been an up-and-down season for him. But he's handling it well. I think he's learning. Obviously it's not easy, but he's doing a good job, he's keeping a good level head and he's putting his work in every week, like he has all year."

In his previous start, Gray gave up seven runs over 3 1/3 innings in an 8-0 loss to Cleveland.

"We're always looking and expecting him to go out and be the guy that we've seen in the past," A's manager Bob Melvin said. "So is he. It's just about going out there and stringing a few performances together that get him going in the right direction again."