The Boston Celtics are in a rebuilding phase and are still undecided on whether or not to trade star point guard Rajon Rondo before the upcoming season's trade deadline.

But while their plans are still unknown at this point, EJ Ayala of Basketball Insiders believe that the Celtics will be very active in 2015 free agency period instead of waiting for big-name players in the 2016 offseason.

Ayala said in a recent chat sessions that the Celtics are expected to address their need for a big man next summer, which means that they could go after big-name free agents like Marc Gasol of the Memphis Grizzlies, DeAndre Jordan of the Los Angeles Clippers or Roy Hibbert of the Indiana Pacers.

"As far as free agency the Celtics have mentioned a need for a big man to anchor the paint at the center position for some time now so it would not surprise me to see them go after someone like Marc Gasol, DeAndre Jordan, or Roy Hibbert if he finds his game on a contract year," Ayala wrote.

However, Ayala added that the Celtics' plan might change completely if they eventually decide to trade Rondo in the upcoming season.

Among the three players, Hibbert is considered as the most realistic target for the Celtics, knowing that the Pacers might let go of him should he fail to perform well again in the upcoming season. Both Gasol and Jordan are expected to get strong offers from their respective teams.

In a recent interview, Gasol said that he is not yet thinking about his contract situation with the Grizzlies. Several teams are expected to give him a call should he hit free agency next summer, but Gasol said that he is only focused on their upcoming campaign in the upcoming season.

"That's so far down the line that it's not on my mind. I just want to do my freaking job every day," Gasol said of his impending free agency via Hoops Hype. "You never know what might happen in seven or eight months. The franchise might go in a different direction. We're going to see how we all feel in July. All of the talk now won't change that fact."