Giants outfielder Mac Williamson is trying to figure out his swing. He’s studying video. Talking with teammates and coaches. Before, during and after games. Taking gobs of batting practice.

Yet, he remains in a terrible funk. In Thursday’s 5-4 loss to the Braves at Oracle Park, a game that was decided in the 13th inning on Austin Riley’s run-scoring single, Williamson struck out five times.

Five times.

Just four others in Giants history have had as many as five strikeouts in a game, from Benny Kauff in 1918 to Brandon Belt in 2013, and that’s not a good club to join for someone competing for the left-field job.

“Maybe I could talk to Riley a little bit to get his opinion,” Williamson said at the end of a postgame interview. “Gotta get some pointers from him. The kid can hit.”

Williamson was kidding, or so it seemed. Riley is one of several young Braves who had their way with the Giants in a four-game series that was dominated by the younger, more athletic visitors. Riley, 22, had three homers in the series and has five in his career, which is nine games old.

Williamson, 28, was given another big-league shot after tearing up Triple-A, but after homering and collecting four RBIs in his May 7 debut, he’s 4-for-43 with three RBIs. More recently, 1-for-23. His immediate future is in question.

“The past week, I’ve had a hard time having a good approach,” Williamson said. “When I’m going well, I’m not late on the fastball. Obviously, striking out five times in a game isn’t fun, especially when you lose, because there were multiple times I could’ve helped the team, especially with (Evan Longoria) on second in the (10th) inning.”

After the game, Williamson didn’t dodge the media. He answered questions about his hitting woes for 7½ minutes.

Clearly, there’s no lack of effort. Williamson said he spent much time with hitting coaches Alonzo Powell and Rick Schu, showed video to his own hitting coach Doug Latta, discussed his mental approach with teammates Stephen Vogt and Derek Holland and spoke with Tyler Austin and Belt during Thursday’s game.

Williamson said he has been “pitched interestingly” — pitchers who usually rely on fastballs feeding him breaking stuff and pitchers who usually rely on breaking stuff feeding him fastballs.

“I feel confident when I go to the plate,” Williamson said. “As a pitcher, when you’re looking up there (at the scoreboard), and the guy’s hitting a buck-20, a buck-30 or whatever, that instantly gives them pretty good confidence. They’re not afraid to throw to me right now. I got plenty of pitches to hit today.”

Williamson is batting .128, and manager Bruce Bochy didn’t exactly give him a vote of confidence.

“I don’t know,” Bochy said when asked what the next step would be. “We’ll talk about it. ... That was a tough day there.

“We’ll huddle up and see what we can do to add some offense here.”

Williamson was given Wednesday off, and Vogt made his second career start in left field. Austin hit his fourth homer Thursday, as a pinch-hitter, a day after he homered into the right-field arcade. The Giants have several other left-field options in the minors.

“His timing’s off. No question he’s in between the fastball and off-speed pitches,” Bochy said. “He’s fighting it a little bit. It’s a tough game when you get in a rut like he was in today. I know he’s battling his tail off to make something happen, but you look for hard contact, and that has not been there for a little while with him.”

Riley had six hits and eight RBIs in the series. His eighth-inning homer off Tony Watson tied the score 4-4, and his opposite-field single off Reyes Moronta in the 13th won it.

Madison Bumgarner got a no-decision after pitching six solid innings and handing a 3-2 cushion to the bullpen.

John Shea is The San Francisco Chronicle’s national baseball writer. Email: jshea@sfchronicle.com Twitter: @JohnSheaHey

Swings and misses Thursday, Mac Williamson became the fifth Giant with five strikeouts in a game. The others: Player Date Brandon Belt July 8, 2013 Glenallen Hill Aug. 20, 1995 Steve Whitaker April 14, 1970 Benny Kauff May 23, 1918