Phil Niekro, the man, was in many ways the opposite of the signature pitch that made him one of baseball’s legendary hurlers over a 24-year Hall of Fame career. His knuckleball was as unpredictable a pitch as any in the game’s history, leaving baffled hitters’ attempts at connecting utterly futile.

But ask anyone who knew Niekro, and they’ll tell you: He was as steady, reliable and easy to connect with as they come.

When Niekro passed away at the age of 81 on Saturday, the baseball world lost not only one of its greatest pitchers, but also one of its greatest ambassadors. Since 2009, Niekro had served as a member of the National Baseball Hall of Fame and Museum’s Board of Directors, and no Hall of Famer was more immersed in Cooperstown than he was.

“He wore the Hall of Fame mantle so well,” said Jeff Idelson, who was Hall of Fame president from 2008-19 and is the co-founder of Grassroots Baseball, a non-profit organization dedicated to growing the game in underprivileged communities. “Here’s a guy that won 318 games, had more than 3,000 strikeouts. And it shows you his humility that when he was elected to the Hall of Fame in 1997, he was wondering what he was doing in Cooperstown.

“He immediately became part of the fabric and culture of the Hall of Fame. Serving on the Hall of Fame Board, being at events, embracing the members, embracing those who support the museum through membership as well as other Hall of Fame members, was all part of his DNA.”

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Niekro was what Idelson called a “chameleon,” in the sense that the Hall of Famer was always sure to make others feel comfortable around him. Humility was at the center of a life in the spotlight, behind one of baseball’s most recognizable names and linked to one of its most unique pitches.

Take, for example, what happened on New Year’s Eve in 1999, when Idelson was shoveling the driveway at his home.

“I hear someone come up behind me, and he asks me, ‘Do you have another shovel?’” Idelson said. “It was Phil Niekro. I didn’t even know he was in town.”

Niekro was in town a lot.

“He was in Cooperstown more than any other Hall of Famer I know,” said Idelson. “To the point where I’d joke with him, saying, ‘If you spend any more time here, you’ll have to start paying taxes.’”

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Only three men in the history of baseball threw more Major League innings than Niekro’s 5,404 -- their names are Cy Young, Pud Galvin and Walter Johnson. Niekro’s mastery of the knuckleball, primarily with the Braves from 1964-83, led to an MLB-best 1.87 ERA in 1967, a runner-up finish in the 1969 National League Cy Young Award race, 245 complete games and 3,342 strikeouts. He also won five Gold Glove Awards.

But all of that still left Niekro wondering how he had made it into such a hallowed fraternity of icons. Once he got to Cooperstown, though, it was as if he never left.

Niekro was instrumental in the development and implementation of the Hall of Fame Commemorative Coin Program in conjunction with the United States Mint in 2014, which was a major fundraiser for the institution. And he was a manager, along with Ozzie Smith, in the annual Hall of Fame Classic, which featured legends taking the field each year during Induction Weekend. Niekro’s team was, appropriately, called the “Knucksies.”

When it came to the fans, no one could match Niekro’s dedication.

“I think you would find more balls signed by Phil Niekro than balls not signed by Phil Niekro,” Idelson said.

Niekro learned how to throw a knuckleball from his father, who would teach him after coming home from the coal mines of southeastern Ohio. And Niekro’s catcher? That was his sister, Phyllis. Family was at the heart of everything for Niekro as he grew up, and so it’s no wonder he became such a great ambassador for the family of Hall of Famers that reunites each July to welcome new members.

There is perhaps no greater compliment for an institution like the Baseball Hall of Fame than the one conveyed to Niekro a couple of days before his induction in 1997. He brought with him hometown friend and basketball Hall of Famer John Havlicek, and as they arrived at the Otesaga Resort Hotel, where all of the Hall of Famers would stay for Induction Weekend, Havlicek was focused intently on something in the distance.

“Havlicek is just looking forward with his mouth slightly open, and Phil asked him, ‘What’s the problem?’” Idelson remembers. “And Havlicek looks at Phil and says, ‘Now this is a Hall of Fame.’”

The Baseball Hall of Fame is revered for its stewardship of the national pastime's history, and a presence in Cooperstown that leads even Hall of Famers from other sports to gaze with awe. And while the Havlicek moment took place on the weekend of Niekro’s induction, it would be Niekro’s own dedication to that venerable institution that would play a significant role in ensuring it would remain awe-inspiring and familial in the years to come.

Niekro was as dependable as they came on the mound, throwing more innings than all but three pitchers in baseball history. And that dependability carried right into his ambassadorship with the Hall of Fame, which lost a giant Saturday.

“I think he’ll be remembered in history as one of the game’s greatest competitors,” Idelson said. “But also someone who believed in humility, humanity and opportunity.”