Kendrick Perkins shares his thoughts on why Ray Allen should be the person to reach out to Paul Pierce, Kevin Garnett and Rajon Rondo for the way he left the Celtics to join the Heat. (0:50)

Members of the Boston Celtics' 2008 title team said Monday it's on Ray Allen to reach out and mend fences as bad feelings linger from when Allen defected to the rival Miami Heat in 2012.

As part of "Area 21" segments during TNT's playoff coverage, Kevin Garnett hosted Paul Pierce, Rajon Rondo, Kendrick Perkins, and Glen Davis on Monday night. In one six-minute segment posted online, the former Celtics openly discussed why Allen has not been part of the plans as the team prepares to celebrate the 10th anniversary of its title.

"I just feel like, it ain't what Ray did, it's how he did it," said Perkins. "We did form a family. We all shed tears together, talked about some of the deepest things -- I'm talking about outside of basketball that the world don't know about. If you felt like you wanted to go that way and [sign with a rival], I just think he could have handled it a different way."

Added Pierce: "I was initially hurt by the whole way everything went down. ... I thought we formed a brotherhood here in Boston. Just how we carried ourselves, not only on the court, but off the court. And I just figured if it was me leaving or KG leaving, then I would have been like, 'Rondo, Perk, Baby, this is what I've been thinking about.' That's what I was hurt by when Ray didn't just at least give us a heads-up about it."

Just a month after the Heat rallied to beat the Celtics in seven games in the 2012 Eastern Conference finals, Allen spurned a more lucrative offer from the Celtics to sign with Miami.

"There was no other Wizards, it wasn't no other Spurs, it wasn't no other Heat," Kevin Garnett (left, pictured with Paul Pierce and Ray Allen) said in detailing why he didn't invite Allen to his 2008 Celtics reunion. "It was all Celtics invited to this." Fernando Medina/NBAE/Getty Images

The Heat won the NBA title in 2013 with Allen playing a key role in the Finals.

"Everybody's asking us, 'Where's Ray?' People don't understand that this is real life for us," said Garnett. "The situation with Ray is very sensitive. I think that when we all talked about doing this reunion tour, we were talking about guys who we consider loyal and part of this group. Just being honest, my two cents, when Ray decided to go to the Heat, I felt like he moved on. And he went to pursue another ring, he got another ring, shouts to him. And that's it. There was no other Wizards, it wasn't no other Spurs, it wasn't no other Heat. It was all Celtics invited to this."

Garnett later admitted that time heals all wounds and said there's no true ill will with Allen. Garnett believes Allen will eventually make amends with his former teammates.

But the Celtics players remain stung by his decision all these years later.

"I think I would have even took it better if he had just talked to us about it," said Pierce. "I don't know how his relationship was with [coach] Doc [Rivers], it was kinda souring at the time because Avery [Bradley] was getting more minutes, so I can understand all that. But I just felt like we should have had a conversation. I think it would have settled over a little bit more. I don't think it would have been as salty.

"Even though it was Miami -- we hated them, we hated Miami and that was our rival, we were going at it with them, LeBron [James] and all them. I just think if we had all just kinda talked about it, it would have been a little different than it is now. Now it's uncomfortable. I haven't talked to Ray in some years now. It's just different."

Rondo, who clashed with Allen during their final seasons together in Boston, was noticeably quiet throughout the segment, even when the rest of the panel encouraged him to speak up.

Perkins, one of Rondo's closest friends, said it was on Allen to make the first call.

"Who going to break the ice? At this point and time, I don't think it's on nobody on here to break the ice," said Perkins. "I actually think it's on Ray to break the ice. If Ray wants to make amends with anybody up here or whatever the case, I think it's on him to reach out and say, 'Hey [Pierce], I handled this wrong. Man, we better than this. Hey Ticket, I handled this wrong. Hey Big Baby, I handled this wrong, or hey, Rondo, I handled this wrong, man.' Just get it past this, man. We won games together, man. We did a lot of things."