Now that Braves rookie reliever Shae Simmons isn’t retiring big-league batters with seeming ease, it might be time to remember just how remarkable it was for him to do so in the first place.

“Sometimes it’s just a little bit of a learning curve,” Braves manager Fredi Gonzalez said after Simmons took the loss in a 3-1 defeat to the Marlins in 10 innings Monday night at Turner Field. “Remember what this young man did (was) coming out of Double-A.”

Simmons, 23, made his big-league debut May 31 and quickly took over the setup role with Jordan Walden on the disabled list. He flourished in his first 20 appearances: 11 hits, six walks, and two earned runs allowed in 18 2/3 innings (0.96 ERA) with 19 strikeouts.

But Simmons has had shaky outings in two of his last four appearances, including Monday’s loss to the Marlins, his second loss in as many appearances. He came on to pitch the 10th inning and gave up a lead-off single to Christian Yelich, walked Casey McGehee and allowed a two-run single to Garrett Jones that turned out to be the game-winning hit.

In his last four appearances Simmons has allowed four hits, three walks (one intentional), and five earned runs in 2 1/3 innings with four strikeouts. He said his struggles boil down to a lack of command on his fastball.

“It hasn’t been what it was when I first got here,” Simmons said. “I don’t know what the reason is behind that. I’m still trying to figure that out.”

Simmons said he may not be getting as much movement on his fastball now. But he said he can’t pinpoint the issue because he’s still locating his off-speed pitches where he wants.

“A lot of the times when I’m struggling, anybody is struggling, is because of their command,” Simmons said. “Maybe it’s something in my mechanics. Maybe it’s (not) slowing myself down and finishing my pitches.”

This is the first stretch of poor outings for Simmons. He didn’t allow an earned run in any of his first seven appearances in spite of pitching in some tough situations. After allowing his first earned run on June 13 he had four consecutive scoreless appearance, and then had seven scoreless appearances in a row after allowing his second earned run of the season on June 22.

Simmons gave up his first home run as a professional, majors or minors, while taking the loss against the Phillies on Saturday and then took another loss on Monday. Gonzalez said he expects Simmons will stay confident.

“I think it’s also a young kid coming out of the bullpen in certain situations, you’ve got to get used to it,” Gonzalez said. “From what I’ve known (of) him since he’s been here, he will be fine.”