The Japanese phenom made only one in his first Major League start: a three-run homer to Matt Chapman in the second inning. He didn't allow a hit in any of his other five innings, leaving the A's little wiggle room for miscues in the field.
But the defense derailed again, this time behind right-hander Daniel Gossett, and there were no excuses to be made. Left fielder Khris Davis held himself accountable for a pair of botched plays he insists he should've executed.
A's primary left fielder Matt Joyce, who made a critical misplay at the position on Friday, was missing from the field the last two games because of ankle soreness. He was relegated to a designated hitter role, leaving Davis with left-field duties.
"Usually he makes those plays," A's manager Bob Melvin said of Davis. "He's done a good job for us tracking balls in the outfield. We envision him more with some DH at-bats, but with Joycie's injury, we played him out there, and he's a better outfielder than he showed today."
Added Davis: "We're in a little bit of a funk defensively, but we'll shake it off and we'll get to the next series and put it past us."
Boog Powell endured his own troubles in center field, and Stephen Piscotty, who let an in-between liner skip past him for a triple on Saturday, appears to still be acclimating to the right-field corner of the Coliseum.
The outfield collectively butchered a long list of plays in this four-game set, the last three claimed by the Angels following the A's Opening Day walk-off victory.
"We've had some troubles," Melvin said. "It's cost us the last couple games."
Oakland's pitchers have subsequently had to work overtime. Gossett wasn't at his best on Sunday, but his numbers would've been better had he had greater help from his defense. Gossett was pulled after four-plus innings, yielding four runs on six hits with two walks and no strikeouts in his season debut.
Ohtani emerged victorious, hanging around the upper 90s and orchestrating an impressive six-inning showing that featured six strikeouts. Following Chapman's homer, the two-way rookie retired 14 of his final 15 batters.
"I thought he had really good stuff," Chapman said. "He showed really good command today. Was able to move the ball in and out, up and down, and we had a hard time getting consistent contact off of him."
MOMENTS THAT MATTERED Double down: Outfield blunders plagued the A's all series, and the Angels managed to capitalize on even more on Sunday. With two outs in the second inning, Andrelton Simmons dropped a bloop single in the middle of three A's players converging in shallow right field. Luis Valbuena then sent a line drive to left that deflected off of Davis' glove. Valbuena was awarded an RBI double, and Jefry Marte followed with a double of his own, giving the Angels a 2-0 lead. Yet another double, again off the bat of Marte, bounced off of Davis' glove to open Los Angeles' two-run fifth.
"I definitely feel like I should have made both of those plays," Davis said. "One was more in the sun than the other, but they were tough plays and I gotta make those. Day games are tough here, but at the same time, we know this field, and I just gotta play better off the sun."
Tacking on: Clinging to a one-run lead, the Angels added insurance in the seventh. Right-hander Chris Hatcher was responsible for the three-run output. With one out, the A's reliever surrendered consecutive base hits to Mike Trout and Justin Upton to put runners at first and second for Albert Pujols, who popped out. But Kole Calhoun kept the inning alive with an RBI single, and Simmons followed with a two-run single.
It was needed insurance for right-hander Blake Parker, who allowed three of the four batters he faced to reach, including Stephen Piscotty on an RBI single, before Keynan Middleton bailed him out to close the game with the bases loaded.
QUOTABLE "Well, the way he pitched today, he deserves it." -- Chapman, on the international attention Ohtani is drawing
SOUND SMART WITH YOUR FRIENDS A's right-hander Yusmeiro Petit inherited two of Gossett's runners in the fifth and allowed both to score. It marked the first time he had allowed an inherited runner to score since May 8, 2016, snapping a streak of 32 consecutive stranded runners.
WHAT'S NEXT Athletics: Right-hander Andrew Triggs is scheduled to make his season debut on Monday against the Rangers, who will counter with former A's starter Bartolo Colon in the first of a four-game series at the Coliseum. First pitch is set for 7:05 p.m. PT.
Jane Lee has covered the A's for MLB.com since 2010.