BOSTON (CBS) — The Celtics season came to an end on Sunday, courtesy of 101-93 loss and a four-game playoff sweep by the Cleveland Cavaliers.

A slow start put the Celtics in a hole they couldn’t dig themselves out of on Sunday, trailing by 10 points after the first quarter and 21 at halftime. The Celtics continued to fight and battle as their season counted down though, with an impressive third quarter in which they held Cleveland to just 13 points and a hard-fought finish to the game itself. The Celtics were within six points in the final minute, making a game that shouldn’t have been very interesting at that point rather interesting.

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But in the end the Cavaliers were just too much for the Celtics to handle, and all the fight in the world couldn’t put the ball in the basket. But that doesn’t mean the season wasn’t a success. After a strong finish to their 40-42 regular season resulted in a trip to the playoffs, head coach Brad Stevens is happy with the improvement he saw from his team throughout the course of the year.

“Having to play from behind the last few months and accomplishing something, then measuring yourselves with the best in the East, we have a lot of information and that’s good,” Stevens said after the conclusion of his first NBA playoff series. “We know individually where we need to improve, collectively where we need to improve. What I take from this year is there was growth, building and progress. Now we have to build on that.”

Stevens said he is very happy with the environment the team put in place this season, but now knows the expectations are going to be much higher next season.

“I’m really pleased with a lot of things and we’ve shown a lot of growth. But none of us signed up for the Boston Celtics for a quick exit,” he said. “The best way to phrase it is I like our progress, but I like to win. I’m disappointed right now, but it’s not at anybody. I’m just disappointed to lose. We have to get better, and get better in every which way. That’s the challenge ahead, because winning is a lot more fun.”

“We’re proud, but we’re not satisfied,” said guard Isaiah Thomas. “It’s frustrating to see the season end like this but we’ve got to build from this next year.”

Here’s what we learned about the Celtics in Game 4, and throughout the series against Cleveland.

Celtics Are Not There Yet… But Getting Closer

No, the Celtics aren’t winning any titles in the near future, especially if LeBron James, Kyrie Irving and the Cavaliers are still in their way. But the Celtics fought hard in all four games and made life difficult for the Cavaliers at times in critical moments, so there is some hope.

It’s obvious the Celtics need more size down low, given how many times the Cavaliers were able to turn an offensive rebound into an extra possession and extra points. We know they need a star of their own to run with a team like the Cavaliers and take some of the offensive pressure off Isaiah Thomas, who was not at his best on Sunday.

Neither of those two are very easy to find, and when you do find them, they don’t come cheap. But that’s why Danny Ainge makes the big bucks, and is probably already mapping out Plan A, B, C and D for this summer. With a great young coach in Stevens and a solid group of young players willing to run through a wall for him, the Celtics are only a few pieces away from competing in the Eastern Conference. That’s not exactly competing for a title, but it’s another step in the right direction for the Celtics.

The Celtics are not close to raising another banner, but they may not be as far as once thought. This is a very important summer in the franchise’s quest to get back to having a Championship-caliber team, but fans should feel a lot better given the growth (and fight) the team showed under Stevens in a very short time.

These Celtics matched or exceeded all the expectations for the season, and sound ready to do the same next year.

Celtics Couldn’t Hit Threes Or Free Throws

As for Game 4, the Celtics couldn’t hit much of anything from long-range — or at the line with no one playing defense.

Boston shot just 3-for-23 from downtown on Sunday, led by Thomas’ 1-for-7 shooting from three-point land. Avery Bradley finished just 1-for-5, making Jared Sullinger Boston’s best three-point shooter on Sunday, checking in at 1-for-4. That’s not going to win many games, and especially not against a team like Cleveland.

If you think those numbers are bad, the Celtics shot just 24-for-37 at the free throw line. Brandon Bass finished the game 0-for-4 from the charity stripe.

However, Thomas was a perfect 12-for-12 from the line, helping him finish with 21 points for the game. Imagine what those free throw numbers would be without Thomas? Yikes.

Maybe Kelly Is Tough?

(Photo by Jim Rogash/Getty Images)

(Photo by Jim Rogash/Getty Images)

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He’s been called soft by a lot of fans and those who cover the game (I like to think I fall into both of those categories, and yes, I have called Olynyk soft, among lots of other things). But Kelly Olynyk showed some fight on Sunday, much to the chagrin of Kevin Love.

Olynyk pulled a bit of a WWE move on Love in the first quarter after the two got tangled up going for a rebound, giving Love’s shoulder a little yank as he tried to keep him from getting the ball. It’s hard to tell if there was any intent or not, but Olynyk doesn’t really come across as a very malicious player.

Evan Turner may have summed it up best:

So hopefully he comes into next season with a much better “boxing out” technique under the basket.

Perk Is Still Perk

If you miss the scowl of Kendrick Perkins, you got to see it again on Sunday. Perk didn’t play much, logging just four minutes, but he was the mean-old Perk Boston fans fell in love during the KG-era.

Perkins set up a mean screen on Jae Crowder early in the third quarter, sending his shoulder and forearm into the C’s forward, and then followed that up with another forearm/slap/point when Crowder started to share his displeasure of the play. Somehow, Perkins wasn’t ejected from the game, but he earned a flagrant foul and received a technical along with Crowder for the post-foul nonsense.

Boston fans let Perkins know that they don’t really miss him (not anymore, at least) with a loud string of boos after the play.

Perkins hasn’t had much success since leaving the Celtics, but he really hasn’t changed all that much.

J.R. Smith Should Expect A Suspension

As much as Kevin Love wants to complain about Kelly Olynk’s play that took him out, he can’t say too much with J.R. Smith in his locker room.

Smith delivered a dirty swing at Crowder as the two fought for position in the third quarter, striking the C’s forward in the head and causing him to awkwardly fall back and hurt his left knee. Crowder did not return, and Smith was ejected after being called for a Flagrant 2.

Now Smith will await word from the league, who will likely be sending a suspension his way.

Crowder’s A Keeper

We already knew that coming into this game, but Crowder was good again in his battle against LeBron James until being sent to the locker room by Smith.

He’s a restricted free agent this summer, but likely has a home on the Celtics after earning Brad Stevens’ trust since coming from Dallas in the Rajon Rondo trade.

A Future For Sully?

 (Photo by Brian Babineau/NBAE via Getty Images)

(Photo by Brian Babineau/NBAE via Getty Images)

Perhaps the biggest enigma on the Celtics is Jared Sullinger (no weight joke intended). He draws a wide range of emotions from Celtics fans and the team’s brass alike, and not all of them are very positive. Both sides were pretty frustrated when a foot injury sidelined Sully for what we thought was the rest of the season back in February.

But Sullinger worked hard and was back for the end of the regular season, and on Sunday, he was one of the best Celtics on the floor. He scored 21 points  on 9-for-14 shooting while pulling down a team-high 11 rebounds in 28 minutes.

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Sullinger saw his minutes increase throughout the series and averaged 12.3 points and seven rebounds. It’s unclear if his future is in Boston, but he helped boost his stock one way or another with a strong postseason.