This story was excerpted from Adam Berry's Rays Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

ST. PETERSBURG -- As the Rays ran out one reliever after another Friday night at Angel Stadium, bullpenning their way through a 9-6 win, Zack Littell turned to Zach Eflin to make an observation.

“I mean, one through eight of the core guys,” Littell said, “all of them have some capacity of back-end experience, which is pretty rare. Even our ‘medium- to low-leverage guys’ in any other bullpen could easily be in the back end.”

It wasn’t that way all season. Tampa Bay’s relief corps looked like the weak link amid an otherwise smooth-sailing start. But the Rays have built their bullpen back into a much more reliable unit, thanks in part to a series of in-season additions.

“Things were in flux for a little while, and I think we've had a few different things happen that have really helped stabilize things,” general manager Peter Bendix said.

The improvement is apparent in the numbers. Consider these stats and where their bullpen ranked in the Majors.

Rays relief pitchers, Opening Day-May 31: 4.32 ERA (22nd), -0.3 fWAR (29th), 4.73 FIP (27th), 1.31 WHIP (18th), 1.9 strikeout-to-walk ratio (29th), 92.6 mph average four-seam fastball velocity (28th)

Rays relief pitchers, June 1-Monday: 3.76 ERA (11th), 2.3 fWAR (10th), 3.90 FIP (eighth), 1.15 WHIP (first), 3.08 strikeout-to-walk ratio (fifth), 95 mph average four-seam fastball velocity (ninth)

“They've done a nice job,” manager Kevin Cash said. “Feel a lot better about our 'pen and the condition that it's in right now than maybe we did two months ago.”

So, what changed? Start with the early-May signing of lefty Jake Diekman, the early-June trade for right-hander Robert Stephenson, the similarly timed return of do-it-all righty Shawn Armstrong from the injured list and the recent reinstatement of 2021 All-Star Andrew Kittredge from the 60-day injured list.

Plus, Pete Fairbanks returned to good health in mid-June after two early stints on the IL. Having him back provided stability in the ninth inning, pushed Colin Poche and Jason Adam back into setup roles and allowed Cash to mix and match with everyone else.

Diekman has brought strikeout stuff from the left side, returning to form after a rough time with the White Sox, and a hugely influential veteran presence. Stephenson has one of the best whiff rates in baseball since being traded from the Pirates, throwing his nasty slider more often and about 4 mph harder.

“It's a special breaking ball that he features, and he's got the confidence to throw it in the zone and then get it out of the zone,” Cash said. “He's not fooling anybody by his pitch selection. They know it's coming. It's just really tough to hit, and it's really tough to lay off when it's out of the zone.”

With a 1.03 ERA in 35 innings, Armstrong has been the “unheralded linchpin of the bullpen,” Bendix said, with lights-out stuff in frequent multi-inning appearances and stints as an opener. And now, Kittredge is back from Tommy John surgery. His first big league outing in 14 months? A 1-2-3 inning to secure a save in extra innings on Friday night, naturally.

“We're adding an All-Star closer to our bullpen, which always is going to make you better,” Poche said. “A lot of those additions were huge ... and I think it's one of those things where, the more quality arms you get down there, everyone else kind of steps up a little bit, too. It's kind of contagious.”

It’s an experienced group, too ... aside from the bullpen’s innings leader, rookie Kevin Kelly. It might be easy to forget the sidearming right-hander (currently on the 15-day IL) was a Rule 5 Draft pickup, especially as he’s held opponents to a .172/.262/.250 slash line and logged a 2.45 ERA over his last 33 appearances.

The Rays are still cycling arms through the last few spots in their bullpen, usually to make sure they have a multi/bulk-inning arm available if a game goes sideways. But when it comes to the core relievers Littell was talking about Friday night, it’s like he said: There are no low-leverage arms.

“It's such a long season, and we know that we're going to play a lot of close games. We're going to have a lot of high-leverage opportunities,” Bendix said. “We can't have one or two high-leverage guys and that's it, because we have far more high-leverage opportunities than that, so guys know that there's going to be chances for them to pitch in important innings and big spots.

“Part of that is their own mentality, knowing, 'It doesn't matter where I am on the pecking order. We're all high-leverage guys.'”