BOSTON -- A’s left-hander Jared Koenig has two Major League starts under his belt. The first came on June 8 against the Braves in Atlanta. The second on Tuesday night in the series opener against the Red Sox at Fenway Park.

The 2021 World Series champion Braves are riding a 13-game win streak, while Boston went 8-2 on its recent West Coast trip. Not exactly a warm welcome to the Majors.

On Tuesday, Koenig gave up six runs on nine hits (including two homers) and two walks over four innings, getting tagged with his second loss of the season in Oakland’s 6-1 loss to the Red Sox.

“It's the big leagues. You're going to face good lineups and have to get outs,” manager Mark Kotsay said. “And for Jared, I think tonight was similar to Atlanta in terms of lineups, in terms of their professional at-bats that they took. Laying off maybe some good pitches down at the bottom of the zone.”

In his Major League debut, Koenig yielded slightly better results than he did against the Red Sox in another four-inning outing. He gave up four runs on five hits and two walks with three strikeouts against the Braves. Koenig needed 76 pitches to get through four in Atlanta, compared to the 96 it took against Boston.

Koenig worked a five-pitch mix in both outings, favoring his curveball against the Braves and his sinker vs. the Red Sox. The 28-year-old threw the sinker 39 times on Tuesday, generating 18 swings and just one whiff. His sinker and cutter played slightly better, with three whiffs on each pitch.

“He didn’t execute as well. He did make a lot of good pitches and didn’t get rewarded when those guys did a good job of capitalizing on the mistakes we made,” said catcher Sean Murphy, who was behind the plate for both of Koenig’s outings. “I'm sure he thinks he can throw the ball better, I’d agree.

"But again, I think there's something to build on there. He's got a mix, he’s got a bunch of good pitches. He just made a couple mistakes tonight.”

Koenig surrendered two homers against Boston. The first came on the eighth pitch of an at-bat vs. J.D. Martinez in the third. After Koenig showed his curveball, sinker, cutter and changeup to the slugger, Martinez fired a 90.3 mph sinker into the center-field seats. The next inning, Rafael Devers rocketed an 88 mph sinker over the Red Sox’s bullpen for a three-run homer and a 6-0 lead.

“I think the sinker for Jared needed to play better tonight,” Kotsay said. “He did get some ground balls, we didn't make plays for him. We had a chance, maybe, to turn a double play in the first and didn't get that out. So I think the next start, he lines up against Kansas City, and hopefully with these two starts under his belt with the experience now, he'll go out with a good game plan and have success.”

Stephen Vogt, who realizes the value of experience as a 10-year veteran, knows there’s brighter days ahead for Koenig.

“This is a kid that knows how to pitch. It's a kid that knows how to fight,” said Vogt, who homered in the eighth. “Hopefully when he goes back out next time, he's got his stuff and is a little more sharp.”

Facing Major League hitters is an adjustment for Koenig, who owns a 2.94 ERA across 33 games in the Minors -- 24 appearances for Double-A Midland in 2021 and nine with Triple-A Las Vegas this season. As far as having to face two potent lineups in his first two starts, Koenig wasn’t making any excuses. He, and his teammates, know the stuff is there. His confidence hasn’t wavered despite the numbers behind his outings.

“I mean those are two great lineups. And both teams [are] swinging the bat very well,” Koenig said. “I know I can get outs. Like confidence-wise, I know I can get outs. Now it's just building off it. … and then like I said, continue to figure things out and pitch my game.

“… Just keep building, keep learning. Obviously, I don't want to give up six runs and nine hits in four innings, but I've got to keep learning from my outings and how I'm feeling, and pitches I'm making. And then figuring out what's been successful and then continuing to build off of that.”