By Matthew Geagan, CBS Boston

BOSTON (CBS) — The Celtics season is over, and that’s a good thing. The 2021 season left everyone feeling green about Boston’s basketball team, and it’s a campaign that is best left in the past.

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We could go on and on and on about what went wrong with the 2021 Celtics, from frustrating injuries that popped up every other day to weekly COVID issues to large stretches of uninspired play. Sure, the Celtics rarely had their best and full lineup available all at once, but there was a time when that was seen as a challenge for Brad Stevens’ team. This year, it was just a convenient excuse to plod through the regular season. And when they lost half of their star duo just ahead of the postseason, it ended any and all hope of any kind of upset in the playoffs.

But now it’s over, and we can shift focus on the future. The good news is the Celtics still have Jayson Tatum and Jaylen Brown, and they’re both incredible pieces to what should be a strong foundation for at least the next 4-5 years.

The rest of the picture is a bit… greyish, similar to those horrendous sleeved jerseys the Celtics had a few years back. For lack of a better phrase, the fireworks have already been lit too, with Wednesday morning’s news of Danny Ainge stepping down and Brad Stevens heading to the front office.

The Celtics wasted no time to make a change, a firm admission that something had to be done. And that should just be the beginning of a pretty wild offseason ahead.

The Next Head Coach

Brad is leaving the bench for the front office. That is pretty shocking. His first order will be to find a new head coach.

The next guy has to be someone who can connect with players. A former player would be wonderful. Many will demand Kevin Garnett take over, because if anyone is going to whip the next generation of Celtics players into shape, it’s a ferocious creature like KG.

But how about Chauncey Billups? He’s been waiting for an opportunity for a few years, whether as a head coach or GM, and spent last season on the L.A. Clippers bench. Mr. Big Shot himself would have some instant credibility in the Boston locker room, and he’d probably even have a spot for Garnett — his good buddy — on the bench.

The Kemba Conundrum

Whoever is making the decisions this summer, their biggest one will be on Kemba Walker. Do they trust that the 31-year-old will be healthy next season after a full summer of recovery, or are they willing to get on their hands and knees and beg someone to take him off Boston’s hands.

Kemba was a breath of fresh air after the Kyrie era, but he just can’t stay healthy. And that’s a terrifying concept considering he’ll be the team’s highest-paid player for the next two years. Trying to deal him won’t be easy, and will likely require the Celtics to include some draft picks and young talent, and also take on a different horrendous contract. None of it’s ideal, but neither is having an oft-injured, undersized point guard who makes nearly $40 million on the books.

Making A Smart Decision

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Ideally, the Celtics could find a way to get Walker off the books and hand the starting point guard job to Marcus Smart. He’s an extremely underrated ball-handler and maybe running the offense and setting up others would keep him from taking so many daggone threes. One can dream, right?

But if the Celtics can’t get Kemba off the books, Smart may be the big domino to fall. He’s set to make a modest $14 million next season, but that’s the last year of his contract. And he’s going to want a lot more in the future.

Boston could opt to package Smart and some others in hopes of shedding salary and making an upgrade somewhere on the roster. But in losing Smart, the team would lose its defensive heartbeat and its longest tenured player. It’s not going to be an easy decision, but could be one the Celtics have to make.

Is Fournier Back? 

Fournier was not great after arriving at the deadline, and not at all what Celtics fans were envisioning with that monster TPE from Hayward’s departure. He was sidelined with COVID issues and never really got into a groove with Boston. Now he’s set to become a free agent, and the C’s need to decide if they want him to be part of the future or not.

He may be their best option, since Boston holds his bird rights. And they really can’t sign any other free agents without some massive roster management elsewhere. A sign-and-trade is always an option, but that may only yield Boston another TPE, and we all now how those go.

What About Bob?

There is so much intrigue and promise with Robert Williams. He’s instant energy whenever he’s on the floor and the ideal center for this team as he develops into a premiere shot-blocker and rim-rattler. If only he could stay healthy.

Williams is eligible for an extension this offseason, but questions about his health make that an extremely difficult decision. And given the bounce he’s shown when healthy, he may be the team’s best trade chip this summer.

Which Young Guns Step Up Next Season?

Given the team’s limited financial flexibility, the Celtics are really going to need some of the youngins to step up next season, and step up big time. The bench was downright laughable for 99 percent of the season, which didn’t help as the team navigated injuries and COVID issues.

At least there is some promise after Romeo Langford and Aaron Nesmith played well over the final month of the season. Langford looks like he’ll turn into a really solid defensive player, and if he can develop a steady three-point shot over the offseason, the Celtics may really have something with the 21-year-old. Nesmith carved out a nice role for himself toward the end of the season, and he could also be in the rotation to start next season. Payton Pritchard will also need to keep growing his game as a floor general off the bench.

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And he’s not really a young gun, but if the Celtics can turn Jabari Parker into a successful reclamation project, then it would really help the team’s depth next season.