Right-hander Ian Anderson, a big part of the Atlanta Braves' rotation last year in their run to a World Series championship, was optioned to Triple-A Gwinnett on Sunday after his struggles this season.

Anderson (9-6) has a 5.11 ERA this season in 21 starts. He last pitched on Friday in the Braves' 9-6 victory over the New York Mets when he lasted 4⅔ innings during which he allowed four earned runs, seven hits, walked four and struck out three.

Before he reports to Gwinnett, Anderson will remain with the Braves on their taxi squad this week and is slated to pitch one of the two games in Atlanta's doubleheader against the Miami Marlins next Saturday, manager Brian Snitker told reporters Sunday.

"We need to get him right,'' Snitker said. "He's a big part of what we've got going on. Hopefully he can take a step back and reassess things and get himself going.''

The Braves, currently in second place in the National League East and holding the NL's top wild-card spot, acquired more rotation depth at the trade deadline last week when they dealt for right-hander Jake Odorizzi.

Odorizzi made his Braves debut on Saturday afternoon, in the first game of a doubleheader, pitching 4⅔ innings and allowing three earned runs, six hits and three walks while striking out four. He took the loss in Atlanta's 8-5 defeat to the Mets and is 4-4 with a 3.76 ERA this season.

The Braves also recalled right-hander Huascar Ynoa from Gwinnett on Sunday to give them an extra arm for Sunday's series finale against the Mets.

Also Sunday, the Braves scratched right fielder Ronald Acuna Jr. from the starting lineup as a precaution because of "lower body soreness." Heavy rain at Citi Field caused the start of the game to be pushed back 30 minutes. Robbie Grossman replaced Acuna in the lineup.

Anderson, 24, is 21-13 with a 3.99 ERA in 51 career starts. He has excelled in the postseason with a 4-0 record and 1.26 ERA in eight starts the past two seasons. That includes a 2-0 record last postseason, including a victory over the Houston Astros in Game 3 of the World Series.

Once at Gwinnett, Anderson will get a chance to work through his struggles in the minors with the hope he can return to the Braves later this season so he can again contribute in the postseason.

"It's tough,'' Anderson said. "I haven't thrown the ball all that well.''

In another move Sunday, the Braves recalled catcher Chadwick Tromp from Triple-A after Travis d'Arnaud suffered a leg injury trying to tag out the Mets' Pete Alonso at home plate on Saturday night in Atlanta's 6-2 loss. X-rays were negative and d'arnaud is considered day-to-day. He was in a walking boot Sunday, but Snittker indicated that he expected d'Arnaud back before Friday's series opener with the Marlins.

Outfielder Guillermo Heredia was optioned to Gwinnett to create a roster space for Tromp.

The Associated Press contributed to this report.