OAKLAND -- Whatever the secret is to beating the Athletics, the Cardinals haven’t found it.

The Cardinals fell to 0-4 against the A’s this season with a series-ending 4-2 loss Sunday afternoon, squandering a mid-game 1-0 lead behind starter Adam Wainwright. The Cards fell 1 1/2 games behind the Cubs in the National League East.

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Wainwright spent the postgame dissecting the back-to-back hit batters he allowed in the fourth inning. It was clear those two pitches are going to weigh heavily on his mind for a bit. Wainwright hit Mark Canha with a 1-2 cutter and Stephen Piscotty with an 0-2 fastball that was supposed to be up and in, but came in too far. Both men wound up scoring on Dustin Garneau’s double.

“We’d just scored [on a Paul DeJong homer], and the last thing you want to do is give it back,” Wainwright said. “I didn’t execute. If I did, I’d never have to make that pitch to Garneau. The inning would have been over.”

By Wainwright’s count, he only allowed two hard-hit balls -- Garneau's double and a Jurickson Profar homer in the sixth. By and large, it was a successful start, except that the Cardinals' offense struggled to support him and there was no “W” at the end.

Even so, the minimal offense might have been enough, were it not for the two hit batters. Wainwright had hit six batters in his first 20 starts, and none of them had scored.

“That was the key to the game right there,” he said. “I have to execute better pitches there.”

Wainwright could have used a little luck, too. With the Cards down, 3-2, in the eighth, Jose Martinez crushed a Joakim Soria pitch toward the left-center-field wall.

“I thought it was out; my teammates thought so, too,” Martinez said. “But this is the toughest park to get out of.”

It was in this case. Canha ran the ball down in center field and the Cardinals didn’t get another man on base.

“You are going to have ups and downs like that,” Martinez said. “You’re not going to win every game. But we’ll come back from these two games.”

Now the Cardinals head to Los Angeles for a three-game set against the Dodgers starting Monday, with Michael Wacha, Miles Mikolas and Jack Flaherty due to pitch. Wainwright sees good things ahead for Cards pitchers, who have been at the hub of an 18-12 run of late. St. Louis swept four from L.A. at home in April.

“We have young pitchers learning,” Wainwright said. “We have some old pitchers learning. And we have pitchers learning on the fly. The way we’ve been playing until the last couple of days, we’ll be good. I like our chances.”