Jeff Green looks back on his short time in Boston with regrets. He should have played with more ferociousness. He could have made a serious difference to Boston’s second unit, but failed to stake his claim to games, failed to prove Danny Ainge right, failed to win over his new team’s fans, failed to make his mark in the Bay State.

“I should have been more aggressive when I look back on it now,” Green told ESPN 980 in Washington, DC (via CSNNE). “That’s what they brought me in for.”

NBA observers have been waiting for Green’s breakout year for years. He sweats talent, exhales versatility and very much looks the role of NBA stud. But he also plays with limited horsepower, an odd sense of indifference hovering over every move he makes and every rebound he does not grab. Some players can play hard without showing much emotion. Tim Duncan, for example, rarely ever pounds his chest or screams obscenities; his passion stays somewhere within, but it’s there. It’s hard to tell whether Green’s passion exists. His facial indifference to everything, his on-court expression that says, “I want to take a bath” more than it says, “I need this rebound desperately,” frustrates fans because it mirrors his play’s passivity.

“Being a young guy in this league,” said Green, “it’s tough coming in where you got Kevin [Garnett] on one side, Paul [Pierce], Ray [Allen], [Rajon] Rondo now who’s been with that team for a long time. It was tough for me to come in and be ‘the man,’ coming off the bench, it was tough. In my mind, I’m thinking, ‘Those guys preach, sharing the ball, sharing the ball.’ It was kind of, ‘You gotta be aggressive . . .’  but I didn’t want to step on anybody’s toes. Now I look back at it now, I should have taken it for a grain of salt and take my slice of the pie. I don’t think I did that when I came into that situation.”

The Celtics didn’t need Green to step into the starting lineup and outshine Pierce, Allen, Garnett and Rondo. They needed an anchor for their second unit, someone who would change games with energy and offensive prowess, and maybe even grab a rebound every once in a while. They got something else, something decidedly worse, something underwhelming if not disappointing.

Now, they need to decide whether to keep Green, and if so at what price. The question should keep Danny Ainge awake at night; though Green failed to impress during his short time in Boston, he still has talent. He’s still 6’9 and athletic, with an inside-outside game that should cause opponents all kinds of fits. You can still look at Jeff Green’s physique and movement and envision a star, even if his production doesn’t tell the same story a quick eye test does. For Ainge, the decision to re-sign Green could come down to more than just basketball. If he lets Green walk for nothing, Ainge will admit his midseason trade failed. Ainge will admit Green did not make the impact he expected. Ainge will admit Green was not the player he believed the Celtics were getting.

Hopefully, Ainge will not let his ego get in the way of making a solid basketball decision. That could mean re-signing Green and hoping he blossoms after a full training camp to adjust to his new teammates. That could mean letting Green walk and saving the money instead. Considering Green’s status as a restricted free agent (the new Collective Bargaining Agreement notwithstanding), Boston’s decision could very well come down to what other teams offer Green. The Celtics will reserve the right to match any offer.