OAKLAND -- There wasn’t much more James Kaprielian could do on the mound Sunday afternoon to position the A’s for a victory.

Striking out a career-high 10 batters with just one run allowed in seven superb innings against the Red Sox, Kaprielian continued his ascent as one of the top rookies in baseball by lowering his ERA to 2.84. The only thing lacking was support from the A’s offense, which was stifled by Boston starter Nick Pivetta and the Boston bullpen in a 1-0 loss at the Coliseum to drop the weekend series, two games to one.

Kaprielian impressed the A’s in his first Major League start, which came on May 12 against these same Red Sox at Fenway Park. At the time, the right-hander’s long-term status in the Majors was uncertain as his callup was more out of necessity after the club was short a starter in the rotation. Since then, Kaprielian has established himself with quality start after quality start.

“He seems to get better and more confident every time,” A’s manager Bob Melvin said. “He kept his pitch count down and got through seven. The more he’s out there, the more confident he gets and the better we feel about him. He was fantastic.

“Against this lineup, this was maybe his best game.”

On Sunday, Kaprielian limited a potent Red Sox offense that entered the day having scored the second-most runs in the Majors to just five hits. His lone run given up came on a double-play ball hit by Rafael Devers in the sixth. Though recent starts had seen him struggle while facing a lineup the second time around, Kaprielian actually seemed to get better as the outing went. He recorded five punchouts over his final three innings and capped the seventh with three strikeouts.

The path to success for Kaprielan was simple. He immediately recognized Boston’s inability to put together good swings on his four-seam fastball, so he just kept throwing it. Of his 97 pitches, Kaprielian relied heavily on a heater that maxed out at 95.2 mph and averaged 92.7 mph, throwing it 59 percent of the time. The pitch was used to finish off nine of his 10 strikeouts and generated 17 whiffs (swings and misses) on the day.

“When you’re getting swings and misses, there’s no reason to change something,” Kaprielian said. “I wanted to stick with my guns and stay in attack mode until they proved that they could beat me. That’s something I’ve learned through every start, just staying with it.”

Kaprielian has displayed a good feel for his pitches through most of his outings in the big leagues. But the true sign of a quality pitcher is what they can do on the days where they might not be at their best. Regardless of how he’s felt on a particular day, Kaprielian has been consistent throughout his early career. Sunday’s outing marked the seventh time he’s allowed two runs or fewer in 10 starts this season.

“That’s just the type of player I want to be,” Kaprielian said. “You watch a lot of these frontline starters around the league, and even when they don’t have their best stuff they’re able to keep their guys in the game and at least give them a chance. I want to be that for this team. 

“I want to be somebody these guys can rely on in a big game. That’s one of the things I’ve been preparing for since high school. You have to be consistent to play at this level. Even if I don’t have my best stuff, you’re going to get the same competitor out there and I’m gonna find a way.”

Matt Olson, who was named Oakland’s representative for the 2021 All-Star Game earlier in the day, led off the ninth with a single against Red Sox closer Matt Barnes and was replaced by Skye Bolt as a pinch-runner. But Bolt was left stranded on third base as the possible tying run after Seth Brown struck out to end the game.

With Sunday’s loss dropping Oakland to 3 1/2 games back of the Astros first place in the American League West, the focus now shifts to possibly the most important series of the year -- a three-game series against Houston at Minute Maid Park that begins Tuesday.

Battling through a rough stretch -- the A’s have now lost 10 of their last 15 games -- the upcoming series in Houston presents a golden opportunity to gain some ground in the standings and generate positive momentum heading into next week’s All-Star break.

“It’s a big series for us,” Melvin said. “We’ve been in first place for a lot of the year but they’ve been in first here recently. It’s a good opportunity for us to catch back up.”