Seth Lugo was largely happy with his season before going on the injured list last month, but since returning he has taken his performance to a higher level.

The results by the Mets’ right-hander have been so satisfactory that a shift in roles has occurred in the last week-plus, with Lugo assuming primary eighth-inning duties as Jeurys Familia tries to rebound from a sluggish stretch.

Even with Familia progressing, manager Mickey Callaway appears in no hurry to displace Lugo from primary eighth-inning duties. Lugo’s latest brilliance came in the Subway Series on Tuesday, when he struck out the side on 13 pitches in the nightcap of a doubleheader.

In all, Lugo is 3-0 with a 2.51 ERA and 0.96 WHIP in 24 appearances this season. But since returning from the injured list on May 31, he has pitched 6 ¹/₃ shutout innings over five appearances, bolstering a bullpen that was in desperate need of a shutdown setup man.

“Right before I went on the injured list I was as confident as I have been pitching and I felt really good about everything, and then obviously I was a little sore,” said Lugo, who missed 12 days with tendinitis in his right shoulder. “But I was still confident with my stuff and what I was going to do, but now I am feeling 100 percent.”

Lugo’s only blip since returning came last week against the Giants, when Callaway summoned him to replace Noah Syndergaard in the seventh inning. Lugo surrendered a game-tying hit for the blown save, and after the Mets’ loss in 10 innings, Callaway blamed himself for removing Syndergaard.

But if there was one Mets reliever other than closer Edwin Diaz to trust in that spot, it was Lugo.

“It’s just like the Lugo of last year,” pitching coach Dave Eiland said. “He got the inflammation out of his shoulder, he’s feeling good and he’s hitting his groove.”

Lugo is hoping he receives more opportunities. To this point, he has pitched on consecutive days only once — April 28 and 29 — and he said there is no reason for team officials to coddle him. Callaway has spoken of utilizing Lugo on consecutive days, but hasn’t followed through since the pitcher’s return from the IL.

“I have been talking to [Eiland] and I have been available as far as I was concerned, and was ready to go,” Lugo said. “I hear a lot of talk about it, but that hasn’t been on my mind at all. I want to pitch every day. If I’m not sore, I’m ready to go. I have been ready, but I appreciate them taking caution, looking after my health.”

Lugo added he understands that after longer outings — he has had eight appearances that lasted at least two innings — it makes sense to rest the following day.

“But after one inning, especially if I am throwing fewer than 15 pitches or so, I should be able to bounce back and I am pretty confident that I can,” Lugo said.

Such a change in usage could benefit Robert Gsellman, who has been a bullpen workhorse this season with 29 appearances.

As Callaway evaluates the team’s eighth-inning options, he said he realizes Gsellman and Familia will be needed at times. But the manager has seen plenty to suggest Lugo should remain the primary option.

“Obviously his stuff is off the charts when he is getting after it and using the ride on the high fastball and the curveball … but I don’t want to pigeonhole ourselves into anything, and the one thing we do know is he’s going to need days off,” Callaway said. “But when [Lugo] is available you will probably see him in that role.”

Lugo said he doesn’t care which inning or innings he pitches.

“It’s nice to have the coach’s confidence, but I still try to maintain the same mentality,” he said. “First inning, eighth inning, fifth inning, it doesn’t matter. I’m out there to execute pitches and execute the game plan.”