Arrieta threw 59 pitches, 40 for strikes, but no changeups. That was his plan.
"That was one of the points of emphasis going in," Arrieta said of his efficient outing. "Establish the fastball, sinker, moving in to righties especially. I threw some good breaking balls and stayed away from the changeup today to focus primarily on the cutter and the curveball, and they were both good."
The curve was sharp, and that's encouraging for Arrieta, who will be one of the Cubs' top three starters.
"I was able to use [the curve] early in the count for early strikes and to set up a couple counts later in the game, third, fourth inning," he said. "I think I got one, maybe three on swings and misses. That's what I was looking for today, and just keeping the fastball down in the zone, and both of those areas were pretty crisp."
It isn't that Arrieta is abandoning the change.
"I wasn't sure how long I was going to go today," he said. "Last time out, [it was] two innings, and it's tough to get it all in. That's why I eliminated it today. We went that direction."
The A's took advantage of an error to score against Arrieta in the first. Craig Gentry singled to lead off and moved up on a throwing error by shortstop Addison Russell, who was cut off by third baseman Tommy La Stella as he ran for the ball. Gentry then scored on Max Muncy's single.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.