WALTHAM, Mass. -- As members of the Boston Celtics' summer league squad walked off the floor following a practice Friday afternoon, team president of basketball operations Danny Ainge and All-Star point guard Isaiah Thomas huddled at midcourt.

There were smiles and laughter. Just hours before they set out on a franchise-altering recruiting trip, the duo seemed loose and excited about the sales pitches they were about to deliver.

From the very moment Boston's 2015-16 season ended with a first-round exit at the hands of the Atlanta Hawks, Thomas had declared a need to acquire more talent. Thomas believed the Celtics were on the cusp of elevating into legitimate contenders, but knew he needed help. Thomas spent the past few weeks texting free agents and gauging their interest in Boston, planting seeds with some players as early as February's All-Star game, when they quizzed him on his situation in Boston.

Ainge and his front-office staff spent years patiently positioning the Celtics for this opportunity. Many Boston fans were upset last month, when the team didn't make a glitzy trade on draft night to bring in more established talent. Ainge pleaded for patience, suggesting that none of the trades were worth giving up assets and that Boston would be better off maintaining flexibility for free agency.

Some scoffed. For two decades, it has been said that big-name free agents would never come to Boston. Sure, Boston's lack of cap space worked against the team for most of those years, but still the narrative continued. But that all changed Saturday, thanks in part to a ballooning NBA salary cap and Thomas' persistence in telling everyone how much he enjoys playing in Boston.

When Al Horford tweeted his intentions to sign with the Celtics at 7:15 p.m. ET on Saturday night -- right around the time Ainge and Thomas were delivering their sales pitch to Kevin Durant in the Hamptons -- Boston became a free-agent destination for perhaps the first time in franchise history.

Horford is set to ink a four-year, $113 million maximum-salary contract. Before this signing, Boston's biggest free-agent splurges were typically former All-Stars on their last legs willing to play for midlevel money. Guys like Rasheed Wallace and Jermaine O'Neal. The 30-year-old Horford, a four-time All-Star, proved that Boston is now a destination.

Now the question becomes: Can the Celtics land the biggest free agent of all?

The Celtics called in the biggest names in Boston sports on Saturday. New England Patriots quarterback Tom Brady sat in on the pitch to Durant, while Red Sox slugger David Ortiz tweeted, "Yo [Durant] sorry I couldn't make the meeting today but Brady will tell [you] they don't call Boston the City of Champions for nothing." Ortiz closed the message with three championship-trophy emojis.

Two summers ago while talking about Boston's desire to add talent, Celtics co-owner Wyc Grousbeck suggested that the Celtics wanted "fireworks." It became the buzzword when Celtics fans lamented the lack of big-splash moves made each July (and again at the trade deadline and draft).

How appropriate that, on Fourth of July weekend, Boston finally got its fireworks.

Could there be an even bigger bang? Boston's sales pitch to Durant was intriguing even before Horford -- maybe not quite enough to distinguish the Celtics from West powers such as the San Antonio Spurs, Los Angeles Clippers and Durant's incumbent Oklahoma City Thunder, but with Horford in the fold, Durant will absolutely have to think even harder about the Celtics.

Even if Boston ultimately strikes out in the pursuit of Durant, it has positioned itself well to take another step forward. According to one ESPN Insider model, Boston projects at 53 wins next season. A deeper playoff run would make the Celtics an even more desirable spot for free agents in the summer of 2017 and beyond.

There's still work for Ainge & Co., but they didn't just land a big-name free agent Saturday -- they changed the perception of the franchise. And Boston got that big name without having to spend assets such as the Brooklyn Nets' picks in each of the next two drafts. That draft treasure chest could keep the Celtics a sustained contender deep into the future.

Yes, Boston is finally a destination.