Though the new-look Cleveland Cavaliers put a beat-down on Boston Sunday, it was still a special day for Celtics fans. That's because before the game, the team retired Paul Pierce's jersey.

Pierce played 15 of his 19 NBA seasons with the Celtics. The Truth helped lead the team to an NBA championship in 2008, and he made 10 All-Star appearances with the green and white. He'll certainly go down as one of the best Celtics ever. 

Though many of Pierce's former teammates and his coach, Doc Rivers, showed up for the jersey-retirement ceremony, one noteworthy figure was missing: Ray Allen. Allen, Pierce, and Kevin Garnett formed a "big three" with the Celtics in 2007, but bad blood between them emerged when Allen signed with the rival Miami Heat in 2012.

Allen wrote a tribute to Pierce earlier this week and said they were both interested in building bridges and putting that bad blood behind them. 

"I did think it would have been great for Ray to have been there," Rivers told the Globe. "But there's just angst right now, and in Ray's defense, I know he thought about coming. I can tell you that, because I talked to him personally. He didn't know if he should. He didn't know if it was the right time. He really didn't want to take anything away from Paul or be a distraction, and he won't be, and that's what we've got to convince him of. If he would have been there, the fans would have cheered for him. That will happen eventually; you've just got to figure out when."

Rivers said he thinks a big three reunion will happen.

At this point, it seems like any beef between Allen and Pierce has been squashed. The big issue that remains is the relationship between Allen and their former point guard, Rajon Rondo. The issue there seems to be personal and have nothing to do with basketball.

It's anyone's guess whether they'll ever mend their relationship.