Green's a beat behind

Jeff Green likely didn't even see the irony in his answer. After a lackluster outing as part of the Boston Celtics' opening-night loss to the Miami Heat on Tuesday, Green was asked how he could be more assertive on the floor.

"Play with more heart, plain and simple," he said.

Tuesday's game should have been a celebration for Green, who sat out all of last season while undergoing surgery to repair an aortic aneurysm. After a stellar preseason in which he showed renewed vigor and potential, Green had a national stage upon which to announce his return.

Instead, he missed all four shots he took, finished with a mere three points and struggled mightily on the defensive end. Green was on the wrong end of a highlight moment late in the first half when a baseline drive was rejected hard by Chris Bosh, leading to a loud slam at the other end for LeBron James.

Green, not surprisingly, was overflowing with emotions being back on the floor for his first honest-to-goodness NBA game in 17 months on Tuesday. But he acknowledged his effort wasn't acceptable.

"I had to deal with a lot of things," Green said. "Adrenaline just kicked in, I got tired quickly. But that's not an excuse. I have to do a way better job."

After a brilliant eight-game preseason showing in which he displayed a consistent aggression at both ends of the floor, Green looked tentative Tuesday. When he was aggressive on the defensive end, he'd hedge too high on a pick-and-roll and leave himself unable to recover as Miami got clean looks or open drives to the basket. That frustration carried over to the offensive end, where he was timid and passed up opportunities.

Like we saw at times during his first go-round with Boston after being acquired at the trade deadline in 2011, Green's confidence started to wane, and the Celtics rode a smaller lineup with the likes of Leandro Barbosa and Courtney Lee getting fourth-quarter minutes as the team put together a fierce rally.

"I didn't like the way I played at all," admitted Green. "It all starts on the defensive end. I didn't feel like I was as aggressive on the defensive end as I should have been. But it'll change."

Considering what he's been through, one bad night shouldn't shatter Green's confidence. It's an encouraging sign that he acknowledged his first-game dud and didn't use his emotions as a crutch.

Even still, he probably should avoid social media today. Green's in a spotlight that's as bright as some of his eye-popping sneakers after inking a four-year, $36 million contract this offseason, and just one poor outing was enough for the overreaction crowd to wash away any goodwill earned during the preseason.

Like the Celtics, Green is a work in progress and no one should overreact to one outing. The preseason -- regardless of the level of competition on the floor -- proved that Green has the ability to be an impact player. And much of what Boston accomplishes this season is likely to hinge on if the Celtics can extract that from him on a consistent basis.

Celtics coach Doc Rivers tried to absorb some of the blame Tuesday, noting: "I didn't think he was very aggressive. Maybe we've got to do a better job."

Rivers has admitted to misusing Green after the 2011 trade. He's suggested that Green's inability to get comfortable was from the coaching staff's reluctance to find a specific position and role for him.

Green's value is in his versatility, however, and the Celtics hope to use him at multiple positions this season. So, much of this is on Green. As he has noted since the summer, he's 100 percent healthy now and enjoyed the benefit of a full camp in Boston's system.

It's on Green to prove he can be more than what he's shown to this point. But for just a moment, let him savor the mere accomplishment of getting back on the court. This is a player whose entire NBA career was in jeopardy 10 months ago, and Tuesday -- regardless of performance -- was a special moment.

The Celtics are back on the court Friday in their home opener against the Milwaukee Bucks, and we can all go back to overanalyzing Green's every possession. Green hopes to show he can be more assertive.

How does he do that? Plain and simple, he just needs to play with more heart.