OAKLAND -- The A’s tried to tolerate their 6-2 loss Friday night to the Angels by focusing on Marco Estrada's six innings instead of the bullpen’s final two.

Estrada, who the A’s are counting on to bolster their starting rotation, blanked the Angels on two hits for six happily uneventful innings -- from Oakland’s perspective. Khris Davis’ two-run, sixth-inning home run -- his third in four games -- and Lou Trivino’s scoreless seventh inning set the A’s on course for their second victory in a row. After all, the A's were 70-2 when leading after seven innings last year.

But it's a new season, so the bullpen must prove itself all over again. That didn’t happen, as the Angels scored four runs in the eighth inning and two in the ninth.

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Joakim Soria, a former All-Star closer with Kansas City, failed to retire any of the four batters he faced in the eighth. That included Kole Calhoun, who doubled home the inning’s first run. With the bases loaded and left-handed-batting Justin Bour due up, A’s manager Bob Melvin summoned Ryan Buchter, the bullpen’s lone lefty. Buchter walked Bour on four pitches to force in the tying run. Andrelton Simmons then drilled a two-run single off Liam Hendriks to put the Angels ahead 4-2. They pulled away with a pair of runs in the ninth off Fernando Rodney, another ex-closer.

The A’s, now 1-3 after opening the season with two losses vs. Seattle in Japan, could cling to Estrada’s effort for positive reinforcement. True to form, of the 18 outs he recorded, 11 were on fly balls -- a style that should suit the right-hander in the spacious Coliseum.

“Obviously, I’m a big fly-ball pitcher. It showed today,” he said. “This is a great ballpark, especially for a guy like myself who relies on pop flies. Not only the ballpark, but [also] the defense behind me. Every ball that was up in the air, I knew it would be caught.”

That was the extent of the A’s satisfaction.

“We had our guys lined up,” A’s manager Bob Melvin said, referring to Oakland’s relievers. “You can’t expect them to do it every time.”

Soria was self-critical.

“I threw five pitches in the strike zone; I threw just one quality [strike],” he said. “They're going to make you pay if you don't throw quality pitches. It's tough to digest, but you have to make quality pitches to get outs.”

Buchter implied that he disagreed with plate umpire Bill Welke’s strike zone.

“That's baseball,” Buchter said. “At the end of the day, they [umpires] can do whatever they want, call balls or strikes, and there's no repercussions. There's no fines. They have absolute job security.”

Buchter said that the A’s could take solace in the fact that this was an early season game which, ideally, will have little or no impact upon the A’s psyche.

“I think the number (of games remaining) is 159 -- plus the playoffs,” he said. “Maybe I'm wrong. Is that right? 158? I’m bad at math. I went to junior college.”