BOSTON -- Celtics president of basketball operations Danny Ainge heard it a million times over his first 13 years on the job: Big-name free agents won't come to Boston. So forgive Ainge if he has enjoyed watching his team take a sledgehammer to that narrative the past two summers.

But what changed? How exactly did the Celtics get to the point where Gordon Hayward and Al Horford uprooted to sign max deals in Boston? What was it about the Celtics that convinced Kevin Durant to invite members of the team to his exclusive Hamptons recruitment party in the summer of 2016?

The fact that Boston finally had the necessary cap space to chase top-tier free agents certainly helped. That the Celtics are positioned for sustained future success because of Ainge's relentless roster construction and asset accumulation didn't hurt, either.

But Ainge says he believes there's one reason above all else that the Celtics have managed to muscle their way into the living rooms of top available free agents the past two summers.

"Because of their fascination with Brad [Stevens]," Ainge said.

Ainge has constructed a roster with some of the league's most unique talent, but his biggest superstar is a 40-year-old head coach who prefers a quarter-zip pullover to complement his athletic shorts.

In less than four years, Stevens has morphed from the Butler Bulldogs' mid-major wunderkind into an NBA savant with the Gregg Popovich seal of approval.

When pitching Hayward this month, and Horford and Durant last summer, the Celtics put a heavy emphasis on the storied history of the franchise. They've called in favors from some of the region's biggest sports stars, like David Ortiz and Tom Brady, to offer a glimpse of what it's like to be a legitimate rock star in these parts. Boston brought along Isaiah Thomas to offer a first-hand testimonial about how playing for the Celtics can change your career.

But in crunch time, when it has been time for the Celtics to close, Boston has often spread the floor and let Stevens go isolation.

"There was just something different about Boston and different about being a Celtic."

Armed with little more than a MacBook, Stevens has led a series of basketball-focused presentations aimed at showing these elite players exactly how he plans to maximize their talents. And that, Ainge believes, resonates more than anything else the Celtics can offer.

"It's from a coach's perspective, from how he sees this player fitting in. And Brad does it through video, he does it through statistics and analytics, and he shows it on the chalkboard," Ainge said. "He shows exactly what he's looking for from that player and how that player can be utilized.

"It's not fluff. And I think the players see that. It's not trying to make a case like, 'You have to come here because of this statistic.' It's real stuff. And I think that that's what players appreciate is that openness."

At the pro level, Stevens remains a master recruiter. Even to those he already has recruited once before.

With the spotlight on Gordon Hayward this summer, the free-agent swingman chose Boston. Ezra Shaw/Getty Images

TO REEL IN the summer's biggest free agent, Stevens and the Celtics called in some of their big guns for the sales pitch on Sunday, July 2.

Hayward and his wife, Robyn, had breakfast with Horford and dinner with Thomas and his wife, Kayla. There was a morning trip to Fenway Park, where the Jumbotron beyond the center-field fence welcomed the Haywards to Boston with shamrocks beside their names. Although Hayward said he's not a "huge baseball guy," the Celtics used the historic ballpark as the backdrop for an influential video that not only showcased the power of playing in Boston, but also featured clips of rival stars like LeBron James and Kobe Bryant discussing the atmosphere at TD Garden.

Boston brass whisked Hayward west to see the future site of the team's state-of-the-art practice facility, which will open next spring, and emphasized its close-to-the-city location that surely resonates with players.

The Celtics then bunkered down with Hayward. Ownership introduced themselves and stressed their willingness to spend into the luxury tax to field a championship-caliber team. Ainge detailed all the future draft picks and assets that will allow Boston to remain well-stocked deep into the future.

But the key part of the presentation came when Stevens took the floor. The coach who turned a teenage tennis junkie into an NBA lottery pick detailed how he could help Hayward -- a first-time All-Star for the Utah Jazz last season -- take his game to a new level. The Celtics showed tape of how exactly Hayward's talents would be utilized alongside Thomas and Horford.

And when the X's and O's were done and the team was confident Hayward felt comfortable with his potential role on the team, Stevens opened up about his own gut-wrenching decision to leave Butler University and how hard that had been for him. Stevens emphasized how rewarding the experience has been for him and his family and how the city of Boston has embraced them.

"There was just something different about Boston and different about being a Celtic," Hayward said last week. "It was just a special feeling when talking about being a Boston Celtic."

Maybe there was always just something different about Stevens.

WHEN THE HAYWARDS touched down in Boston earlier this month, they were greeted in baggage claim by two familiar faces: Stevens and Celtics assistant coach Micah Shrewsberry, who was an assistant at Butler during Hayward's time there.

The plane he traveled on from Miami might as well have been a time machine, because Hayward felt instantly overcome by nostalgia.

"We get to the terminal and it's late at night and my wife and I are greeted at the terminal by Brad and Coach Shrews," Hayward said. "It's immediate familiarity and comfort. It brought back memories of when I was being recruited in high school by Coach Brad.

"It started out like that and that was just a really cool feeling to kind of be doing it over again, this time at the next level."

The Celtics believed they were well positioned to make a strong pitch to Hayward because they knew what made him tick. But Ainge was likewise concerned that Hayward's familiarity with Stevens might work against the team.

"It could hurt us, too, in the fact they had such a strong bond years ago that you might not want to jeopardize that bond by getting into the stress and pressure of a completely different circumstance," Ainge said. "So I didn't know how that would go, quite honestly."

But, in a way, Stevens had it easier this time than he did a decade ago. Stevens has often told the story of recruiting Hayward when he was just a skinny teenager viewed as a bigger prospect on the tennis court than the hardwood, at least until a high school growth spurt. Hayward is the son of two Purdue products and Stevens had to really sell his Butler program, especially considering how much Boilermakers gear he used to see Hayward wearing.

"I was there when he was a puppy, when he was a junior in high school and he was a good tennis player and nobody was recruiting him [for basketball]. And it was like, 'You think we should offer that guy a scholarship? Nobody's looking at him. Nobody's even in the building.'"

It's wild to think about how different things might be if Stevens wasn't the first to see the potential in Hayward. Those around the Butler program insist that Stevens' early faith in Hayward was maybe the deciding factor in his decision to choose Butler over a bigger school like Purdue.

"I was there when he was a puppy, when he was a junior in high school and he was a good tennis player and nobody was recruiting him [for basketball]. And it was like, 'You think we should offer that guy a scholarship? Nobody's looking at him. Nobody's even in the building,'" Stevens said before his first pro battle with Hayward in 2013 while gushing about his continued progress.

"It was probably a good decision, in retrospect. He's awfully good."

Hayward committed to Butler on June 1, 2007, months before his senior year, so that he could focus on trying to win a state championship in tennis.

"I went and watched him play tennis, and he was a top eight or nine player in the state of Indiana," Stevens said. "And the one time I saw him play, he got beat, and he was wearing a Purdue hat and Purdue shorts, so I wasn't very happy with him after that day.

"You saw the physical tools, and you know the mental side of things is high level. Then it was a matter of when he starts really committing himself to basketball full time, how good can he get? Question answered."

Stevens deserves a good amount of the credit for putting Hayward on a path to success. A decade after that first recruitment, Stevens' faith was rewarded by Hayward agreeing a second time to let Stevens try to take him to new heights.

Ultimately, the Butler bond worked in Boston's favor. Both sides seemed genuinely excited to be resuming the recruiting process a full decade after the original pursuit.

"I think that it's a really an unbelievable thing to be sitting with a guy in your offices when he's 16 or 17 years old in the [college] recruiting process, then to again be sitting with him when he's 27 years old and to see just the change and the maturity and the great questions and the thoughtful ways that he was looking at all of his options and all of his opportunities," Stevens said. "Trying to talk to him about why we thought this was a really good situation for him."

In the aftermath of formally inking his four-year, $128 million maximum-salary contract last week, Hayward joked about how different things are now from the initial recruiting process. As a high schooler, he had to ask his parents to enable texting capabilities on his flip phone because college coaches were bombarding him with messages.

Text messages, though, remained a big part of this recruiting process. Stevens said he texted Hayward starting at midnight on July 1 and then tried to keep in touch as Hayward made his visits to meet with the Heat and Jazz.

Still, on July 4, Stevens was like the rest of Celtics (and Butler) nation.

"I sat and waited with my fingers crossed," he said.

Brad Stevens and Gordon Hayward took Butler to the national title game. What strides will the duo make with the Celtics? Michael Conroy/AP Photo

IT'S NO SECRET that Stevens is an NBA hit-maker. In his short time in Boston, he has made Jordan Crawford the sort of player that could win an Eastern Conference Player of the Week award. He harnessed the talents of Evan Turner and Kelly Olynyk enough so that teams paid them a combined $120 million the past two summers. Stevens helped Thomas morph from overlooked sixth man in Phoenix into someone who finished fifth in MVP voting last season while earning All-NBA second-team honors.

Hayward knows well how Stevens can maximize talents. He had done it already at Butler, helping Hayward emerge as the lottery-caliber talent that the Jazz picked with the ninth pick in the 2010 draft.

Hayward is one of the most efficient scorers in the NBA. According to Synergy Sports data, he averaged 1.091 points per play last season, which ranked in the 91st percentile among all NBA players.

Nearly a quarter of his plays came as the pick-and-roll ball handler, and Stevens is sure to tap into that talent, even when Hayward shares the floor with Thomas. Sure, it will take some time for both players to figure out when and where their shots come from, but both are versatile enough to play on and off the ball.

The Celtics haven't had a player like Hayward to pair alongside Thomas the past two seasons: someone who can create his own shot. Avery Bradley was a fine two-way player but much of his offense came on spot-up shooting and backdoor cuts. Hayward's ballhandling opens up new possibilities for Stevens and gives the Celtics a primary scoring option when Thomas is off the court.

Hayward rated well defensively, too, allowing 0.842 points per play, according to Synergy data. That ranked him in the 83rd percentile despite playing one of the league's most unforgiving positions. Hayward will be tasked with helping to defend elite scorers, but Boston has loaded up on versatile wings and can throw a variety of bodies at the likes of LeBron James or Giannis Antetokounmpo.

"I know [Brad is] a genius when it comes to [maximizing talents], both offensively and defensively," Hayward said. "I couldn't be more excited with the guys we have on the team and I'm ready to get to practice already and start learning and competing with these guys."

AINGE WAS MAKING his way back to Boston earlier this month to greet Hayward when a stranger approached him at the airport.

"He seemed real excited," Ainge said. "I'm not even sure he had an affiliation to Butler or anything, but he did say he's from Indiana, and he couldn't wait to watch Celtics games this year. I've heard that a lot lately."

Maybe the only people more excited than those in New England could be those residing in central Indiana, Butler Bulldogs territory.

Since almost the very moment that Stevens left Butler to take over as head coach of the Celtics on July 3, 2013, there has been chatter among those with ties to the Butler program about whether he and Hayward might eventually work together again. So when Hayward elected to explore free agency this summer and declared Boston would be one of the three teams with which he would meet, those with connections to the Bulldogs wondered if their paths might actually intersect again.

When he announced his decision to join Boston in an article for The Players' Tribune, Hayward cited "unfinished business" with Stevens as part of his motivation to rejoin forces.

"Some of us would probably say, 'What took so long?' Because we probably wanted it to happen for both of them," Butler athletic director Barry Collier said. "On the other hand, there's so many pieces involved that you don't know if it'll ever happen. It's just exciting that it has and we'll see what the future brings."

Still, even those around the Butler program marvel at how serendipitous a reunion it is. It was a decade ago that Stevens, then a top assistant at Butler, first convinced Hayward that he had NBA potential while recruiting him to the Bulldogs.

The paths of Hayward and Stevens diverged for seven years, their interactions severely limited during the past four because of NBA tampering rules. But now they're together again and those around the Butler program are convinced the Butler bond played a key role in Hayward's decision.

"Unless you've really lived it, it's hard to explain to people on the outside," said Matthew Graves, an assistant under Stevens at Butler who now coaches at the University of South Alabama. "[Outsiders] get a feel for [the Butler bond]. You're getting a feel for it. But unless you're really part of it, it's really something truly special."

Graves now lives 750 miles south of Butler's campus, but his phone number's 317 area code is a reminder of his central Indiana roots. And in the weeks leading up to Hayward's decision, his phone was bombarded with calls and texts from Butler associates wondering if he thought Hayward might choose Boston.

"Everybody is extremely excited," Graves said. "I guess Butler people are going to still watch Orlando now that Shelvin Mack is there, but it's a nice opportunity to get to see both Gordon and Brad together again on the same team. I know everybody is really looking forward to it."

Graves is already planning to make the two-hour trek to New Orleans when the Celtics play the Pelicans next season.

After news of Hayward's decision to join Boston emerged, Butler's men's basketball account tweeted out a picture of Stevens and Hayward in Butler blue with a hashtag #GoDawgs. The University later tweeted, "The Boston Bulldogs has a really nice ring to it."

Even the account of the team's official mascot, Butler Blue III, tweeted a picture of the bulldog sitting at center court at TD Garden.

"I think Indiana probably has an affinity for the Celtics going back quite some time," Collier said. "In large part that was developed through [Larry] Bird's years there. But now with these two Butler guys, as we would coin them, we're excited. On our campus, there's really a buzz of excitement for them and to be able to see how they might win games for the Celtics."

The excitement was on display at Butler. Now it's coming to Boston.

"When you already have that kind of built-in trust and chemistry," Graves said, "amazing things can happen."