ATLANTA — Dedniel Núñez was a key piece to the Mets bullpen for two seasons, but his recent return to the team after Tommy John surgery rehab hasn’t proceeded as smoothly. 

Wednesday night, he had an ugly seventh inning that helped send the Mets to a series defeat with a 6-3 loss to the Braves at Truist Park. 

Núñez entered with the Mets behind 3-2 and allowed three runs — including two home runs — while retiring only one batter. It followed an appearance five days earlier in which he allowed two earned runs in one inning against the Pirates. 

Such is the volatility of the Mets bullpen following the trade deadline deals that sent Luke Weaver, Huascar Brazobán, A.J. Minter and Brooks Raley elsewhere. In addition, Devin Williams is on the injured list with a right shoulder strain. 

“There has been good and bad from this whole process,” Núñez, who underwent ligament replacement surgery (for the second time) in July of last year, said through an interpreter. “I think when you have been out as long as I was it kind of takes a little longer to find your rhythm, to kind of find that execution. I haven’t been executing my fastballs as well as I wanted to.” 

Núñez allowed consecutive homers to Mike Yastrzemski and Austin Riley in the seventh before Ronald Acuña Jr. hit a ball off the fence for a double that became the third Braves run in the inning. 

“Some pitches in the heart of the plate have gotten hit pretty hard,” interim manager Andy Green said. “[Núñez] is going to be fine. The opportunity to get out there and continue to pitch, he’s going to get that. When we look forward to next year, he’s going to be a big part of what we do. He has good stuff. He has kind of paid for middle-middle mistakes right now. He will keep grinding and get it right.” 

Big showings in Cleveland and Pittsburgh and an impressive opener at Truist Park this week offered the Mets hope that surging bats would lead to a third straight series victory. No such luck. 

The Mets were shut out Monday — and before that, Saturday in Pittsburgh. In their six victories on the trip, they averaged 8.3 runs. On this night, they did not place a runner in scoring position until the ninth inning. Three solo homers accounted for their runs. 

Zac Thornton was respectable, allowing three earned runs on seven hits and one walk over six innings. The rookie lefty has pitched to a 2.78 ERA and completed at least six innings in five of his last seven starts. 

“It was a gritty performance for him,” Green said. “That was not his best stuff. It wasn’t his best strikes and he continued to grind.” 

Thornton allowed a homer to Lane Thomas with two outs in the second inning for the game’s first run. Thomas crushed a high cutter over the left field fence — the third homer allowed by Thornton over his last four starts. 

The Mets deficit increased to 2-0 in the third. Thornton walked Acuña Jr. leading off the inning, and Drake Baldwin singled before Matt Olson’s double-play grounder brought in the run. 

Acuña’s RBI single in the fifth gave the Braves a 3-0 lead, but the inning could have been worse for Thornton after he allowed a leadoff single to Austin Riley and a single to Sean Murphy. Acuña was thrown out trying to reach second following Francisco Lindor’s cutoff on the hit. 

Luis Torrens’ third homer on the road trip, a solo blast in the sixth, got the Mets to within 3-1. Luis Robert Jr. homered in the seventh for the second Mets run, and Bo Bichette went deep in the ninth. 

Núñez entered for the bottom of the seventh and surrendered consecutive homers to Yastrzemski and Riley that placed the Mets in a 5-2 hole. Núñez was charged with a third run in the inning after Baldwin stroked an RBI single against Jefry Yan. 

“It wasn’t that I was all over the place where I wasn’t necessarily executing my pitches,” Núñez said. “I left some pitches in the zone. I was trying to attack and they did damage.”