WALTHAM – From the moment they came together, Kevin Garnett, Paul Pierce and Ray Allen have been asked about windows. How long is it open, is it closing, is it shut, and so on. Together, they have won 234 regular season games, nine postseason series, two Eastern Conference championships and one NBA crown and all anyone ever wants to talk about is how much they have left.

Four years in and going on five, the big three are still standing. While they won’t approach the legacy of the original Celtics’ trio of Bird, McHale and Parish, they are well past the point of a novelty act. But their time is coming to an end and everyone knows it.

“We’re not goofing around, I hate to say it that way, but we want to win now and literally our window is closing,” Doc Rivers said during the team’s media day on Tuesday. “There’s no doubt about that. We have to take advantage this year.”

Garnett and Allen are in the final years of their contracts. That doesn’t mean that they won’t return, but the reality is that their expiring deals are the primary reason why the Celtics will be in line to have a significant amount of cap space to rebuild rather than tear down. Team president Danny Ainge has meticulously planned for this event, constructing a roster for this season that is short on star power and even shorter on long-term contracts, but long on versatility and experience.

“I think our guys still feel they can win and we’ll just have to see,” Ainge said on Monday. “It’s hard to know when guys are getting older how much they have left. They surprised me the last couple of years. I remember two years ago when it wasn’t looking very good the second half of the year and they got to Game 7 of the NBA finals on the road. These guys have a lot left in the tank. I think we’ll know more about that a month or two into season.”
Allen, Garnett and Pierce have heard it all before. Garnett said he hasn’t thought about the future beyond this year. Pierce said he saw more basketball in his teammate’s futures and hoped it would be in Boston. Allen, as always, was philosophical.

“This year, just like last year and the year before, you guys have asked that same question: Is this our last opportunity?” Allen said. “Every moment is our last opportunity because nothing’s promised.”

Unlike previous seasons, media day was subdued. The other member of the core – Rajon Rondo – did his press duty on Friday when the team returned for a surreal three days of training camp while Ainge hastily assembled the roster. There was little news to be had on Tuesday and the outsized personalities of years past we’re gone. That may not have been a coincidence.

“I think we added a lot more experience off the bench, a lot more veteran guys,” Pierce said. “I thought a year ago we had a lot of immaturity with our bench roster, and they brought inconsistent play with them. These guys are a lot more experienced and bring a lot more professionalism on a day-to-day basis. I think they're going to be great. We're going to need them with the back-to-backs, the games crammed in a short period of time, we're going to be asking a lot of them.”

Keyon Dooling, Brandon Bass and Chris Wilcox are the veteran newcomers. Marquis Daniels is back along with Jeff Green and Sasha Pavlovic and there is hope that young players like Avery Bradley, JaJuan Johnson and E’Twaun Moore can provide more than just practice legs.

“If you play well, you’ll probably play and if you don’t play well you’re probably not going to play,” Rivers said. “So, Avery has to play well. He has to perform well in practices. He has to execute out stuff defensively and offensively. JaJuan and E’Twaun, all of them. And if they do that, they’ll play. I’ve never had a problem playing a good player and that’s what Avery has to do.”

With 66 games in 124 days, Rivers will have to use his entire roster simply to survive the season. He hinted at using what he called “crazy lineups,” when Rondo was off the floor and every veteran that Ainge acquired has the ability to play more than one position. All those new faces led to this class Garnett quote:

“Timing is everything and chemistry is something that you don’t just throw in a frying pan and mix it up with another something and throw something on top of that and then fry it up and put it in a tortilla and put it in microwave, heat it up, give it to you and expect it to taste good. You know?”
Garnett looked around at a giggling media horde and added, “If y’all don’t know what I’m talking about, then you can’t cook and this doesn’t concern you.”

But beyond the jokes, the Celtics veterans had a somber tone discussing the challenges that lie ahead. Pierce, Garnett and Allen are proud vets. They’ve been around long enough to have experienced two lockouts and all three took active roles in the union’s fight during the collective bargaining agreement. They’re not happy about the condensed timeline to start the season or some of the chaos happening around the league.

Allen: “I feel very rushed. I can’t say I’m particularly happy with the way things have transpired over the last two or three weeks, but I think everybody’s in the situation where we have to do the best with what we have. There’s nothing more you can do about it but prepare yourself physically and mentally.”

Pierce: “They’re probably should have been a period where you had a free agent signing period, then training camp. I just thought Christmas Day was something that was really pushed among the player as a key date and that’s why we’ve been rushed the way we’ve been rushed.”

Garnett: “Everybody’s paying attention to the Chris Paul situation. I don’t know why everybody’s shocked. [David] Stern’s pretty adamant about how he wants to do things. Now everybody has a voice about it or has an opinion about it.”

Asked if he was choosing his words carefully, Garnett replied, “I’m being very up front with you. I’m not coming off mad. I’m not coming off emotional. I’m coming off as a professional. I want you to respect that.

He continued, "I’m going to use a Doc Rivers saying here, and I hate this saying, but you’ve got to get past mad. Come in and do you job and understand what this and that’s what everybody’s going through.”

Whatever you want to say about the big three, you can’t question their commitment. They all showed up in excellent shape and took their offseason work seriously. That was never really in doubt and neither is this: If the Celtics are going to compete for a championship all of them -- and Rondo -- are going to have to be at their best come spring. No matter how many changes are in place, the Celtics’ season will ultimately come down to them.