ATLANTA — Mike Kimbrel vividly remembers when he first realized that his son was special. 

"He was 5 and he threw a baseball over our house," Kimbrel told FOX Sports. "Even though it was a small house."

Craig Kimbrel was special once, and he still is.

In the city that fostered his legacy, against the organization that identified and nurtured his greatness, the 35-year-old closer collected his ninth career postseason save Saturday in the Phillies' NLDS Game 1 win over the Braves. 

That one didn't count toward Kimbrel's 417 career regular-season saves, good for eighth on the all-time list. Just another 23 will catapult him into the top five. Already, he is considered one of the greatest relievers of all time, a man who revolutionized the sport with a magical fastball and, somehow, in the twilight of his magnificent career, continues to compile outs for a team with World Series expectations.

The years have sapped Kimbrel's once eye-popping velocity; time has taken a few miles per hour off the fastball that once sat in the upper 90s. Sometimes, the ripcord curveball lacks the requisite bite. Other times, his command betrays him. And every so often, he gives off a whiff of being washed. 

Last October, Kimbrel was so unreliable with the Dodgers that the NL West champs left him off their playoff roster. The strikeouts had vanished and all that remained was hard contact. So when the Phillies scooped him up as a low-risk free agent this past winter, hoping the legendary flamethrower had some gas left, it was far from a headline addition.

But Phillies general manager Dave Dombrowski, who traded for Kimbrel years ago in Boston, thought there was something left. That faith was rewarded. Kimbrel hurled 69 innings for the thriving Phils, striking out 94 batters with a 3.26 ERA and 23 saves. And here he is, back in October, keeping the flame alive.

"If he wasn't throwing a baseball, I'm not sure what else he could possibly do." former teammate and Dodgers reliever Joe Kelly told FOX Sports.

But while the fastball might not look the same, Kimbrel himself does. His iconic pre-pitch set-up hasn't changed a bit. That trademark hunch toward the catcher, the throwing shoulder pinned up to his ear, the right forearm dangling down at a 45-degree angle like an Alabaman marionette. Ask any opposing hitter, it's as imposing as ever.

When he first broke into the big leagues with the Braves in 2010 as a 21-year-old, Kimbrel turned heads and missed bats thanks to a game-changing unicorn fastball and a soul-snatching knuckle-curveball. His first five seasons with Atlanta were perhaps the greatest run by a reliever in MLB history: a 1.43 ERA in 294 appearances with 186 saves and an outrageous 14.8 strikeouts per nine innings. Only two pitchers, Félix Bautista and Aroldis Chapman, had a higher strikeout rate this season. 

Again, Kimbrel did this over five.

What we didn't know at the time was that Kimbrel's heater was the future of the sport. Way before advanced pitch tracking revolutionized the game, Kimbrel was throwing a high-spin fastball from a lower release height with a whole lot of carry. Nowadays, that type of pitch is all the rage, identified early in amateur players and nurtured throughout minor-league development systems. 

"He got lucky throwing that one. It was just his natural throwing motion," Kelly said. "And now we have numbers to show why it's so good. It's pretty cool." 

Matt Strahm, one of Kimbrel's bullpen mates on the Phillies, added: "His stuff changed the game. He might not have specifically, but when people saw what he was doing, it was like, well, f--- the fastball down and away."

Here's how Kimbrel's fastball works: Hitters anticipate gravity's effect on the ball, expecting it to have some natural downward vertical movement on its journey to home plate. But a high-spin heater negates that gravitational impact and creates a phenomenon commonly referred to as ride. When such a pitch comes from a lower release height, it only amplifies that phenomenon especially when it's located at the top of the strike zone or above. Think about Braves ace Spencer Strider and his fastball.

So, even though Kimbrel doesn't have the hair-raising velocity anymore, the angle and vertical movement on his fastball (not to mention things like command, composure, etc.) still allow him to rack up outs. The life of a reliever is inherently volatile — each year, each outing, each pitch is completely beholden to random chance. But while Kimbrel is no longer a guaranteed lockdown guy, he's far from a has-been hanging on by a thread.

Kimbrel is a vital part of a dynamite Phillies bullpen, a group that limited Atlanta's historic offense to zero runs over 5 2/3 innings Saturday. For that success to continue, Kimbrel can't fold. On a team full of high-paid stars and potential future Hall of Famers, Kimbrel is expected to be the last man standing, the guide to the final out, the rock in the ninth.

The arm has changed, aged, evolved and endured. The task has not. And, fortunately for the Phillies, neither has Kimbrel's demeanor. 

"As soon as that phone rings, and he f---ing slams his pants down over cleats, you can see his intensity," Strahm said. "We could be talking about hunting in the seventh, but then that phone rings and he flips the switch. That's what makes people great."

Jake Mintz, the louder half of @CespedesBBQ is a baseball writer for FOX Sports. He played college baseball, poorly at first, then very well, very briefly. Jake lives in New York City where he coaches Little League and rides his bike, sometimes at the same time. Follow him on Twitter at @Jake_Mintz.