ANAHEIM -- When the Angels won the series opener against the A’s on Thursday, marking their fourth straight victory, manager Brad Ausmus was hoping the club would keep it rolling against a divisional opponent ahead of them in the standings.

But the Angels were outplayed over the next three games, including a 12-3 drubbing in the series finale on Sunday, causing Ausmus to come away frustrated by his club’s play. The Halos were outscored by a 23-5 margin over those three defeats, and they fell back under .500 at 42-43 after reaching a season-high two games over .500 on Thursday.

• Box score

“You win the first game of the series against the team you're chasing, it's kind of unacceptable -- we need to play better than that, quite frankly,” Ausmus said. “Any of us that put [on] that uniform and go into that dugout, we need to do a better job. We're chasing Oakland among other teams in the hunt. We just got back over .500 and we lose three in a row. We just have to be better. Simple as that."

Heaney’s troubles with homers continue

Andrew Heaney hasn't had much trouble missing bats this year, but he has been plagued by home runs since returning from left elbow inflammation in late May. Heaney again racked up the strikeouts against the A’s, getting eight in six innings, but he gave up a costly three-run homer to All-Star Matt Chapman.

Heaney, making his seventh start of the season, was charged with five runs on six hits and one walk, falling to 1-2 with a 5.40 ERA. The three-run shot to Chapman was his ninth homer allowed this year, and he's served up at least one in all but one of his outings.

“I think that’s how teams are playing now," Heaney said. "That’s how balls are going. If you can avoid those big swings, that’s what teams are shooting for. If you can avoid those, you’re going to have good nights. Obviously, I haven’t done a very good job of that. Keep working.”

Heaney surrendered an early run in the second after hitting Mark Canha on the foot with a curveball to lead off the frame. Chad Pinder doubled on the next pitch to score Canha. Heaney later put two runners on with nobody out in the fourth and got a key double play, but he gave up a two-out RBI double to Ramon Laureano.

The homer came in the fifth with Heaney ahead in the count, 1-2. Heaney threw a changeup off the plate, but Chapman reached out and drove it the other way for his 21st homer of the year. It was the fourth time this year Heaney surrendered a homer with two strikes. Heaney explained he wanted the pitch down and away, but it stayed up.

“I think it’s just more execution,” Heaney said. “Sometimes you get caught up a little bit in some of the pitch selection, you know, and it just comes down to making good pitches.”

Offense quiet yet again

Heaney didn’t get much help in terms of run support, as the Angels’ offense was held in check for a third straight game.

Shohei Ohtani connected on a pair of solo homers -- marking his third career multihomer game -- and Kole Calhoun came through with a two-out RBI single in the sixth, but that was all they could muster. Mike Trout came up with two runners on and two out in the seventh, but he struck out looking on a 3-2 slider from reliever Joakim Soria.

“We've kind of ran into the last three guys, and they've gone out and done a good job,” Calhoun said. “You've got to kind of tip your cap to them, and put this one behind us and go get 'em tomorrow. It's not what you want to do, especially when we get back to .500 or above it and trying to go on a little run. But we've got a chance to go to Texas and Houston, and hopefully finish on the right foot going into the break."

Seventh inning spirals out of control

Reliever Cam Bedrosian also struggled in the eighth before leaving the game after being hit by a Robbie Grossman comebacker that glanced off his glove and hit his face with two outs. Bedrosian earlier gave up an RBI single to Laureano with two outs, and he was also hurt by an error from second baseman Tommy La Stella that would’ve ended the inning.

Bedrosian, who said after the game that he was fine, exited with the bases loaded. Justin Anderson then came in and got Josh Phegley to hit a fly ball to right, but it hit off Calhoun’s glove for a two-run error. After a Marcus Semien walk, Chapman followed with a three-run double, giving him a career-high six RBIs.

"It wasn't a great inning," Ausmus said. "Today was just kind of a slow painful death. It just kept spiraling in the other direction. It wasn't a lot of fun to be there."