So last night, the 2008 Celtics began their "reunion tour", as KG, Paul Pierce, Rajon Rondo, Kendrick Perkins, and Glen "Big Baby" Davis all appeared on KG's TNT "Area 21" segment, and they spoke as a group for the first time about the situation with Ray Allen.
As most of you know, KG, Pierce, and Allen came together in the 2007-2008 season, forming the first of the modern "Big 3's". The Celtics already had Paul Pierce, and traded for Ray Allen & Big Baby from the Sonics, and then soon after traded for KG from the Wolves. The Celtics absolutely killed it in the 2007-2008 season, and went on to win the 2008 Championship over the Lakers in a great Finals, with Pierce earning Finals MVP honors. The Celtics core seemed to be not only unstoppable, but a true family unit. In the following season, they would have a great regular season, but fell in the 2nd-round of the playoffs as KG was hurt shortly after the All-Star break.
They weren't done however, as the next season, 2009-2010, with Rondo emerging as a genuine star in his own right, they found themselves back in the NBA Finals, despite being the 4th Seed in the East (largely due to Doc Rivers resting his stars for more minutes and games then they should have been). After jumping out to a 3-2 lead in the Finals over the Lakers, they dropped Game 6 after Kendrick Perkins suffered a devastating knee injury early in the game, and blew a big lead in Game 7, as Kobe Bryant and the Lakers took home the title, giving Bryant his 5th and final ring.
Their core players returned for the 2010-2011 season, and they also added veterans Shaq and Jermaine O'Neal, as Perkins injury was likely going to keep him out until February of 2011. The acquisition of Shaq eventually lead to Perkins being traded to the Oklahoma City Thunder that season, and the Celtics then struggled down the line as Shaq found himself battling injuries. After sweeping the Knicks in Round-1, they lost to the eventual NBA Champions, the Miami Heat, in 5 games in the second round, and Shaq retired after the season.
This is where the story gets good - because although the Celtics had struggled the season before, they felt it was largely due to the injuries they dealt with, and they still believed that they were as good as they needed to be to make a run for the title. Not only that, but with the Heat forming their own "Big 3" in the 2010-2011 off-season, in D-Wade, Lebron James, and Chris Bosh, the Celtics developed a genuine rivalry and hatred for Miami.
So after the 2011 season ended, Ray Allen rejected the Celtics offer to resign with them, and headed South to play with the Heat in pursuit of another ring. The Celtics core of Pierce, Garnett, and Rondo took that very personally, because according to them, not only did Ray Allen not even give them a heads up, but he joined their bitter rival, and seemingly turned his back on them. The rest, is history, as Allen went on to win the Heat Game 6 against the Spurs, which led to him adding another ring in 2012, and then was a vital role in the Heats' 2013 Championship as well. Not only did the Celtics feel a continuing resentment towards the Heat as the two teams continued to battle to be the Eastern Conference Champions, they felt their hatred shift towards Ray Allen himself, as according to them, not only did Allen never tell them of his plans, but he still, to this day, has not reached out to make amends.
The Celtics 2008 reunion tour will continue on, without Ray Allen, but according to their '08 squad (aside from Rondo who I assume genuinely hates Allen), all Allen has to do is reach out if he wants to move forward.
You can see the full interview of what the '08 squad has to say about Allen below, and truthfully, I don't blame them one bit for their resentment.