Celtics face an important offseason

A long summer, spiced with yet another very important draft, awaits the Celtics.Jim Davis/Globe Staff/Globe Staff

To the Cavaliers, a championship ring. Maybe.

To the Celtics, a growth ring. Also maybe, with fingers crossed, and left wanting for an 18th championship ring.

There are no guarantees in the NBA, or anywhere else in sport, but the Celts packed up on Causeway Street late Sunday afternoon resolute that they were the better for taking on the Cavs, despite the fact that they were swept out of their first-round playoff series with pro forma efficiency by Lebron & Co.

“The best thing that I take from this year is that there is growth, there’s building, there’s progress,’’ said Celts second-year coach Brad Stevens. “Now we have to build on it. That’s the challenge, right? Now continuing it and building on it.’’

A long summer, spiced with yet another very important draft, awaits Celts boss Danny Ainge. The Cavs series proved his team is more than a piece away from contending for a top seed in the East or, to dream, reaching the NBA final. He needs a rim protector. He needs a true, elite ballhandler and scorer (Isaiah Thomas, though sensational in spurts, was exposed as a 1A vs. the Cavs). He needs some more stout-hearted bigs (and even some littles) to bring down offensive and defensive rebounds.

Oh, and a guy or two who can nail the three-pointer, maybe? In a four-game series in which the Celts lost by an aggregate 37 points (including 101-93 in Game 4), they were outscored by 51 points, (117-66), from three-point range. The confident, sure-handed Cavs launched 122 shots from outside the arc, while the Celts fired but 86, roughly a 30 percent difference in total attempts. While true that the series was not won or lost on the fight for Trio Grande, it did underscore Boston’s, shall we say, short-man complex.

“It sucks being swept, 4-0, but you can look back at it and we were in every game basically,’’ said the ever-willing Jonas Jerebko. “Like [Game 4], I don’t know how many free throws we missed (13), how many open threes we missed (20 misses outside the arc)…those go in and and we got it. ’’

If the 4-0 sweep is indeed going to prove a growth ring, we will not know that for a year or two, and it all goes hand in hand with what moves, sleight-of-hand or otherwise, Ainge can conjur in the offseason. The Celts unloaded their two highest-profile players in Rajon Rondo and Jeff Green a month apart during the season, looked as if they might tank for a top draft pick, only to arrive in the playoffs as the Accidental Qualifiers.

Moving ahead now, and validating getting whacked by the Cavs as a growth ring, won’t come by accident. The Ainge moves will have to be deliberate, defined and, most important, maintain the traction that finally developed in the wake of the Rondo-Green moves.

“We have a lot of information and that is really good,’’ acknowledged Stevens, who implement perhaps the most critical improvement of all, restoring the club’s grit and work ethic. ‘’We know where we can be better. We know individually where we need to improve. We know collectively where we need to improve.’’

The glass, one of the key “need to improve’’ areas, was a Celtic shortcoming throughout the series. The Cavs owned a 93-73 advantage in Games 1 and 2, a point the Celts addressed much better in the two games on Causeway Street (Cavs, 95-90). Again, the total numerical difference for the series (Cavs, 188-163) was not overwhelming, but it was telling. The Cavs earned much of the edge on the defensive board, where they pulled down 17 more balls than the Celts.

“We got some experience,’’ noted Stevens. “But we didn’t get it against just a run-of-the-mill team. We got it against a team that a lot of people think will come out of the East, with some of the best players in the world…that stretches you, and that’s a good thing.’’

What will it mean?

“I think it will be very valuable,’’ said Celtics starting center Tyler Zeller. “You are preparing for next year and I think it gives you an idea what you are preparing for, all those little things that you have to take care of. You have to get rid of them. Regular season you can get away with them, but in playoffs you can’t.

“It was very quick, very intense, but at the same time it is still basketball you played your whole life and you have to continue to work and continue to play hard.’’

Of the four games, the Cavs mounted their largest lead in the series Sunday when they amassed a 21-point bulge (57-36 ) at the half. The Celts followed that with a plucky third quarter—the worst, by far, turned in by the Cavs -- and had the crowd believing they could at least force a return trip to the Q.

“It taught us we have a chance,’’ said Avery Bradley, summing up what the series meant overall. “That we can play against anybody if we’re playing the right basketball. I mean it is just as simple as that.’’

Simple to define, but not necessarily to enact. Gang Green still has a way to go. A series is over, the serious work begins.

“More experience. Obviously, playing together,’’ said Avery Bradley, assessing the club’s needs. “If we had this team together the whole year, we would be battling for second or third position in the East. I think we have to keep building our reputation.”

It will all be handed back to Stevens in September, with perhaps five or six new faces on his 15-man roster, the potential turnover a reflection of the number of missing pieces that must be found.

But April 2015 was a place to start for a team that desperately needed to reestablish itself and get a fandom to believe again. If the growth ring comes true, believing will be the first step in dreaming.

“I like our progress, but I like to win,’’ said Stevens. “So I am disappointed right now....disappointed to lose. We have to get better, we have to get better in every which way. That is the challenge ahead, because winning is a lot more fun.’’