Middle relief is not sexy. A bullpen doing its job quietly hums along, not drawing much attention. Even closer Craig Kimbrel — “Welcome to the Jungle” entrance music and flame graphics notwithstanding — brings mostly a workmanlike attitude to the most glamorous position in the pen.

But let’s pause with the Braves leading the National League East and awaiting the arrival of the second-place Nationals for a weekend series to reflect on the dominant work of the Braves’ relievers.

They carry the best ERA of any bullpen in the major leagues at 2.38. At 22-9, they are the only bullpen in baseball without double-digit losses.

The Nationals know it better than anybody. They haven’t scored a run in 32 innings against the Braves’ bullpen this season. The closest they came was loading the bases on a 36-pitch night from Kimbrel last week in Washington in the third game of a Braves sweep.

Believe it or not, this was supposed to be a patchwork job.

This is a bullpen that lost top left-handed set-up men Eric O’Flaherty and Jonny Venters to season-ending Tommy John surgery in a one-week span in May.

“We had the two best lefty relievers in the game of baseball go down,” Braves catcher Brian McCann said. “They’re the two best. And for these guys to step in their shoes, it’s great to see …”

“They’ve been in roles that are unfamiliar to them, late-game pressure situations, and they’ve all handled them as good as you can possibly handle them.”

Jordan Walden proved to be that much bigger of an offseason acquisition. He worked through some shoulder soreness about the time O’Flaherty and Venters went down and came back dominant with his upper 90s fastball.

Left-hander Luis Avilan continued to come into his own. He has a 1.09 ERA and a streak of 35 consecutive appearances without allowing an earned run, since May 21, the day O’Flaherty had his surgery.

“We knew it was going to be tough for the rest of the year when we lost O’Flaherty and Jonny,” Avilan said. “And we were like ‘OK. We have to step it up and try to show everybody that we can do that job, too.’”

David Carpenter joined the Braves’ bullpen in April as “added depth” when Avilan had some cramping in his hamstring and again when Luis Ayala went on the disabled list with an anxiety disorder related to high blood pressure.

Carpenter could throw upper 90s, too, but really took off once he honed his slider with some advice from Tim Hudson. Carpenter watched Hudson throw his slider in the bullpen warming up for a start in San Francisco and asked him about it the next day. Hudson suggested changing his thumb placement.

“Having the thumb a little bit too far under the ball was causing it to pop out,” Carpenter said. “(Now I get) better depth on it, it allows me to stay on top of the ball.”

Carpenter now is a pitcher who manager Fredi Gonzalez will go to for multiple innings and in late innings when Kimbrel or Walden need rest. (Walden hopes to return from a bruised right hand for the weekend series against the Nationals.)

The Braves’ bullpen got key contributions from rookie left-hander Alex Wood, and when he returned to the rotation, general manager Frank Wren brought in veteran left-hander Scott Downs in a trade with the Angels. Downs hasn’t missed a beat in six scoreless appearances as a Brave. Mix in steady work from Ayala and Anthony Varvaro, and the combination is working.

Downs, 37, said this is the best bullpen he’s been a part of, and he’s pitched in relief for the past nine seasons, including six in Toronto with the likes of closer B.J. Ryan.

But ask Downs, any of the other relievers or McCann, the tone is set by Kimbrel.

“When he gets on the mound, Craig Kimbrel expects to go three up, three down,” McCann said. “And you can see it in his face. You can see it when he walks out those doors. His intensity is on a whole ’nother level, and I think he leads without even leading. Guys look at that and they’re like, ‘Man, I need to step my game up when I’m on the mound and focus like that.’”

Kimbrel needed only seven pitches to dispatch three Phillies in the ninth Wednesday night, helping Carpenter out of a jam and collecting his league-leading 38th save in the process. He also surpassed John Smoltz for the franchise record by converting his 28th consecutive save.

Bullpen coach Eddie Perez likes to kid Kimbrel that he started throwing harder this season when Carpenter showed up. Kimbrel doesn’t dispute it. He just smiles. And that’s part of why this whole thing works.

“Yeah, I can’t let anybody else try to throw harder than me,” Kimbrel said. “We push each other. We push each other to get better each outing. That’s just part of it. That’s how you become better, never settle for doing good. You want to do better the next time out. We all kind of have that mentality.”

Pastornicky update: Tyler Pastornicky was scheduled to undergo an MRI on Thursday on his sprained left knee, but the Braves were not expected to update his condition until Friday. Pastornicky injured his knee after colliding with Jason Heyward on a fly ball to right field Wednesday night.

The Braves are holding out hope that it’s a day-to-day situation and they won’t have to make a roster move, with Dan Uggla already on the disabled list headed for laser eye surgery. If the Braves do have to put Pastornicky on the DL, they likely would turn to Tommy La Stella, who is hitting .339 in 64 games for Double-A Mississippi.