Allen chose the rival Heat over the Celtics late last week for less money, surprising a majority of Celtics fans.
“I was surprised, but I wasn’t utterly shocked,” Grousbeck said. “Let’s face it, he was not necessarily going to start. As Doc put it, he felt somehow that he was slighted possibly in the recruiting process in this offseason. … If Doc’s report is correct, Ray felt he was second fiddle to first, Avery Bradley  and then Kevin Garnett , so he decided to go to our arch-rival for less than half the money, so be it.”
Added Grousbeck: “I would not blame him [for his negative emotions]. I’ve said to friends of mine and people that I work with over the last few days that the trade deadline and the fact that he was almost traded, it would bother me, if I was Ray. And he has every right to go down to Miami. And we have every right to try and beat those guys.”
There have been rumors circling that Allen and Rajon Rondo  did not get along.
“Let’s put it this way, if Ray had come back … he would have played fine with Rondo,” Grousbeck said. “There was a number put out and there were also emotional issues out there. There was a price tag put out there [reported to be $27 million for three years], it just wasn’t one we could get to.”
Following are more highlights from the conversation. To hear the interview, go to the Mut & Merloni audio on demand page .
On Allen’s legacy: “Let’s put it this way, Red Auerbach  told me personally and told players in front of me, ‘It’s the name on the front of the jersey, not on the back.’ I think Ray always put the Celtics first and it was never about himself and I think if we’re going to be successful we have to keep doing it that way. We’re going to band together, we’re not going to cut down Ray Allen in any way. We’re going to say the name on the front of your jersey just changed, but you’re always a Celtic to us.”
More on Allen’s departure: “We’re thrilled with what he gave us. We respect his decision. I think it’s fantastic because it just riles me up that he went down to our arch-rival for half price — what’s that about? I want to make it not an easier path to a ring, I’m going to make it a harder path to ring if I have anything to say about it.”
On his relationship with Allen now: “It’s a very friendly relationship and we respect Ray. Not going to say we wish him the best, but we wish him a difficult season in Miami.”
On the Celtics’ future: “We are 24/7 trying to make this team dominant. And I will say the one thing that has really got me smiling right now is reading people saying [Allen will] have a better chance for a ring down in Miami. We’ve added some talent, we’ve lost some talent, but I don’t know anybody who can predict what’s going to happen in the East next year, and I think we’ve gotten better. …
“We played very well as a team for the last five years with these guys together and I’m just about as excited about next year’s team, the way it’s shaping up. I’m excited about where it’s going and it’s going to be worth watching. …
“We brought back our starting five and are planning to add Jason Terry  and Jeff Green  to that. We also brought a couple of good draft picks and maybe yet another player in the next few days. So I’m pretty happy about the team.”
On Green’s return: “We’re really excited to be making progress with Jeff and his agent, David Falk. David has chronicled how pleased he and Jeff and Jeff’s family were about the treatment with the Celtics. We’re really happy with how they handled it on their side and we’re really glad that he’ll be coming back. It’s not pressure or expectations I don’t think as much as hopes and making the investment in the future of the team, getting younger, getting more athletic and getting very skilled. … His body of work in his few years in the league has been very solid or potentially fantastic.”
On Bradley’s shoulder surgeries: “This is exactly what we knew was happening since May, but I guess it hadn’t been out there exactly in detail. … You just do one at a time with shoulders, I’m told, and we always knew he was going to get both of them done, so it’s not a surprise.”
On who will play center: “We did go out and draft Fab Melo, just as an example, in the first round, who could be a center project, and Danny [Ainge] in the press conference said that [Jared] Sullinger might be able to bang down there at that position. Size is always at a premium in the NBA. … So it may be center by committee.”
On Garnett’s return: “We wanted to make sure that we had the chance if he wanted to keep playing [all three years of his contract] he’d been in green. He’s obviously been a focal point of our offseason and once he was in place with an agreement it enabled us to go out and aggressively build the rest of this team. It’s pretty exciting to have him back.”