Buck Showalter basically shrugged when the subject of the surging Braves was broached, as if he fully expected the 2021 World Series champions to eventually make an extended run to challenge the Mets in the NL East.

Despite his team’s double-digit lead getting slashed over recent days, Showalter remains extremely confident in his first-place club, which returned home from a 5-5 western trip to dispatch the Brewers, 4-0, Tuesday night at Citi Field.

Fueled by previously slumping Chris Bassitt’s best and longest start of the season — and two more RBIs from Pete Alonso — the win temporarily extended the Mets’ cushion to 5 ½ games in the NL East while the sizzling Braves sought to grab their 13th straight victory Tuesday in Washington.

Bassitt had gone winless with a 7.62 ERA over his previous five starts, but he allowed three hits and struck out seven over eight shutout innings (109 pitches) before Drew Smith recorded the final three outs to complete the shutout.

The Mets (41-21) held a 10 ¹/₂-game divisional lead on June 1 before departing for their 10-game western swing. Showalter certainly wasn’t surprised that the Braves have remedied their championship hangover after a 23-27 start through 50 games.

“I know you might roll your eyes. I haven’t looked at the standings since we left [for the road trip], except for the plane coming back,” Showalter said before the game. “Maybe it’s on purpose. But things like that, whether the Braves or the Phillies or whoever, it’s a given to me and to us.

“I mean, you’re all gonna seek your level in a baseball season. Everybody knew they were too good to [not] get there.”

The Phillies also have heated up to climb back above .500 following the firing of manager Joe Girardi earlier this month. The Mets won’t see the rising Braves again until July 11 nor the Phils until Aug. 12. Showalter insisted the team is looking solely at the slate immediately ahead of it, with six more games to play on this homestand against the Brewers and the Marlins.

“I don’t know what the players choose to do and look at. But we do maintain a lot of focus on what we do, and we can’t do anything about that. We have to stay focused,” Showalter said. “Again, we’re getting ready to play one of the best teams in the National League and maybe in baseball in Milwaukee.

“You’ve got to put yesterdays in the rearview mirror, and what somebody else is doing, to us it’s a given. If we said something to our guys about it, they’d go, ‘No you-know-what.’ You don’t want to be Captain Obvious to them. They don’t need to know that. Because they already know things like that. There’s no secrets.”

It certainly was no secret that Bassitt’s early-season ERA had ballooned from 2.34 on May 14 by more than two full runs to 4.35 over his previous five outings. But the righty permitted just one hit and faced the minimum 12 batters through four innings before Hunter Renfroe’s double-play ball negated a Francisco Lindor error to keep the shutout bid going through the fifth.

The Mets had jumped on Milwaukee starter Adrian Houser for three runs in the opening frame, featuring run-scoring hits by Alonso and Jeff McNeil and a sacrifice fly by Eduardo Escobar.

Following a heads-up play on the bases in the fifth by Starling Marte to advance to second on Lindor’s fly ball to left, Alonso ripped another RBI single to center for his 12th RBI in nine games and his 59th of the season, tying Cleveland’s Jose Ramirez for the major league lead.

Bassitt was aided defensively by another double play to get through the sixth, started by a nifty flip from second baseman Luis Guillorme to Lindor. The former A’s All-Star then struck out two in each of the next two innings to maintain the four-run advantage through eight.