The concept of having a “Big Three” has swept the NBA landscape in recent years.

However, some people forget that the original “Big Three” was formed by Danny Ainge of the Boston Celtics when he acquired both Kevin Garnett and Ray Allen to join Paul Pierce in the summer of 2007.

That trio led the Celtics to their 17th championship in 2008 and created the model that still exists. Although the Golden State Warriors one-upped them by creating a “Big Four”, many will remember the Celtics’ trio for what they were: three of the best players to ever suit up alongside each other.

Despite the title that the trio brought Boston, their relationship fell apart when Allen left to sign with the Miami Heat in the summer of 2012. He famously signed there for less money and instantly became hated by many fans in Boston as a result. Garnett made it very clear over the years that Allen’s decision still upsets him to this day, but Pierce has generally kept quiet about it.

When the Celtics retired Pierce's jersey on Sunday, former coach Doc Rivers and teammates Rajon Rondo and Garnett were present. But, Allen was not.

On ESPN’s The Jump on Monday, Pierce said he didn’t mind Allen’s no-show. “To each his own,” he quipped.

A day later, Allen took to Instagram and crafted a lengthy congratulatory post for No. 34.

“What we did in 2008 was special! Not only by Boston standards but by professional sports standards,” he wrote. “The truth is, without any one of us on that team we would’ve never been able to do the unthinkable. Going from last place in one year to winning a championship is unfathomable. But, we did it! WE did it- Paul Pierce, Kevin Garnett, Rajon Rondo, Tony Allen, P.J. Brown, Sam Cassell, Glen Davis, Eddie House, Kendrick Perkins, Scott Pollard, James Posey, Leon Powe, Gabe Pruitt, Brian Scalabrine, Doc, Danny, everyone at the Celtics Organization, our wives, children, families, the Fans in The City of Boston and yes, me.”

He also brought up the difficult times and the decision that destroyed his Celtics legacy.

He continued, “Over the last few years I have been berated, lambasted and had my name smeared. You may not want to hear this, but I will always be a Celtic. (Fact). I will always cherish the bonds that I shared with all of my teammates and the people in the city of Boston. (Truth). We all gave everything we had. We all won and we all raised the 2008 NBA Championship banner together. (Ubuntu) Paul Pierce is the first guy that welcomed Kevin and me with open arms into his atmosphere from day one and we never looked back. Paul and I have spoken about our time together as teammates- going to battle night after night knowing we could count on one another and we have also talked about my decision to leave during free agency- a choice I made for my family.”

Allen made it clear that, despite the rumors, he still has a lot of love for his former teammate.

He concluded, “Despite what you may have heard or read or what is rumored- there is nothing but love. Paul and I are more interested in building bridges than putting up walls. To Paul, number 34, Congratulations on having your number raised up to the rafters. I salute you for your commitment to the city of Boston and to us the 2008 NBA Champions #thetruth”

Although Allen didn’t show up to Pierce’s ceremony, it was a classy act to congratulate him in such a public manner.