BOSTON – “Everything changed the day Kevin arrived in Boston.”

Wyc Grousbeck, managing partner and co-owner of the Boston Celtics, couldn’t have said it any better than with those eight words.

Everything changed when Celtics general manager Danny Ainge struck gold by acquiring Kevin Garnett, a 10-time All-Star and former league Most Valuable Player, from the Minnesota Timberwolves on July 31, 2007.

Everything changed because Garnett wasn’t just an elite basketball player; he was also an elite leader, a man who shifted the culture of an entire organization in one fell swoop.

“Very few players can affect an organization like Kevin did here in Boston, both on and off the court,” Ainge said Friday, the day of Garnett’s retirement from the NBA. “He led our team by example every day with his drive, his passion, and his relentless commitment to winning.”

Such characteristics shined bright from the moment Garnett stepped foot inside Boston’s practice facility. Teammates listened. Coaches listened. Everyone listened when KG spoke.

And when he played? Opponents were in for a long night.

Garnett joined forces with Paul Pierce and Ray Allen to create the newest rendition of Boston’s “Big Three.” The trio clicked in a fashion that no other trio had ever clicked before. It didn’t take months for them to build an unbreakable bond; instead, it happened immediately.

Boston, behind MVP-level play from Garnett at both ends of the court, jumped out to a 29-3 start to the 2007-08 season. It went on to win 66 of its 82 games during the regular season.

Less than 11 months after Garnett’s arrival and the creation of the new Big Three, the Celtics had captured their 17th world championship banner and restored Celtic Pride. They did so by easily ousting the longtime nemesis Los Angeles Lakers in six games of the NBA Finals.

Garnett, Pierce and Allen were All-Stars that season. KG took home Defensive Player of the Year honors, the first of any player in the franchise’s storied history to do so, and could have easily won league MVP honors as well.

All of this took place in conjunction with Garnett fully understanding his role on the team. He was tasked with being Boston’s modern-day Bill Russell: a defensive captain and top rebounder. Garnett gracefully accepted a reduced role – though still a substantial one – at the offensive end for the betterment of the team.

Still, Garnett put up impressive averages of 18.8 points and 9.2 rebounds per game during his first season with the team.

“While always putting team ahead of individual,” Ainge said, “Kevin earned his place among the greatest players in Celtic and NBA history.”

Garnett’s arrival in Boston changed everything for the Celtics. The lasting impact of his work ethic, his leadership and his team-first mentality still oozes from the walls of the team’s facility. He was the driving force behind the restoration of Celtic Pride, and that pride has not waned since his exit from the team during the summer of 2013.

While the Big Ticket’s arrival in Boston changed everything for the Celtics, it also changed everything for the NBA. Following Ainge’s acquisition of Garnett, teams began to understand that it would be nearly impossible to defeat a Celtics squad with a healthy Big Three unless it had a Big Three of its own to run onto the floor. Thus, teams around the league began gearing up for an arms race to duplicate Boston’s recipe to success, and superteams have been born across the league ever since.

Today, Garnett announced his retirement from the NBA after 21 historic years of service, matching the longest career of any player who has ever passed through the NBA. His playing days may be over, but more than nine years after that memorable 31st day of July in 2007, his impact continues to be felt in Boston and around this league.

That is the mark of a living legend.