"If you look at the percentage of strikes to balls and where the location was and repetition of his delivery, he was never in any trouble," Cubs manager Joe Maddon said. "They just hit two homers."
Arrieta's first 12 pitches were strikes, and he only needed seven to retire the side in the first inning. Yadier Molina hit a two-run homer in the second, and Carpenter belted another in the third. Carpenter's blast ended an 0-for-28 regular-season stretch against Arrieta.
"He's a really good hitter," Arrieta said of Carpenter. "I made a mistake, middle away, and it's kind of what he's looking for. It's not the ideal first hit I'd like to give up to him, but you've got to give him a little credit there."
There may be some razzing when the two get together again.
"I'm sure he's been waiting to get off the schneid against me for awhile," Arrieta said. "You make a mistake, and every now and again, they'll make you pay for it."
In Arrieta's first outing of the season on April 4, he threw six scoreless innings against the Cardinals at Busch Stadium. Since then, he's given up 27 earned runs over 38 2/3 innings in seven starts, resulting in a 6.28 ERA (he has a 5.44 ERA overall).
"I believe he's going to be fine," Maddon said of the right-hander, who won the National League Cy Young Award in 2015. "I believe it's going to be like a snap of the fingers and everything will fall back into place."
Maddon doesn't need to see the 2015 Arrieta, but he was looking for an uptick in velocity.
"That's when you'll see him take off again," Maddon said.
On Sunday, Maddon was OK with what the stadium radar gun indicated, with Arrieta's fastball registering at 92, 93 mph.
"By far, for me, his best performance of the year," Maddon said.
"It was probably some of the best stuff I've featured this year, good command," Arrieta said. "There were just a couple mistakes that I made that were capitalized by those guys for a couple two-run homers."
Carrie Muskat has covered the Cubs since 1987, and for MLB.com since 2001. She writes a blog, Muskat Ramblings. You can follow her on Twitter @CarrieMuskat and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.