Celtics’ Big Three of blame: Kyrie Irving, Brad Stevens, Danny Ainge

Both Brad Stevens and Danny Ainge had roles in this disappointing season, but they were hardly alone.Jessica Rinaldi/Globe Staff file

The epitaph for the underachieving and overconfident Celtics was offered by coach Brad Stevens following a five-game steamrolling by the Milwaukee Bucks: “I did a bad job.”

Stevens owned his failure, but he’s far from alone.

If they produced a documentary about this Celtics team it would be entitled: “I Did a Bad Job: The Story of the 2018-19 Boston Celtics.”

This was a complete franchise failure, and to borrow from Jaylen Brown’s clapback at Kyrie Irving, it starts from the top to the bottom. This basketball Chernobyl, a catastrophic meltdown, doesn’t happen without cascading failures and incorrect actions by multiple parties. Everyone from these Celtics can say they did a bad job. But if there is a Big Three of Blame, it’s Irving, Stevens, and Danny Ainge.

It goes without saying that we all wish Ainge, the Celtics president of basketball operations, a speedy recovery and sustained good health following the scary heart attack he suffered during the Bucks series. That’s more important than basketball.

Yet, when evaluating the Celtics collapse, you can’t leave out this flawed team’s architect. Ainge did a disservice to Stevens with this roster. The Celtics were an impressive collection of talent, not a T-E-A-M, team.

There were too many built-in contract concerns and agendas, too many positional and personality conflicts, too many starters and not enough role players. The roster lacked rim protection and featured a surfeit of players who defined their contribution only through offense.

It seemed that Ainge left it to Stevens to sort out how the talent he had accumulated would coalesce into a functional team. It never did. I’m not sure it could have.

If you’re going to build your team around a mercurial, iconoclastic talent such as Irving, then the rest of the roster has to have stability for the coach. This one didn’t. To maximize Irving’s abundant talent, you need the requisite role players and a real running mate that he considers a peer to relieve him of some of the burden (post-injury Gordon Hayward isn’t that guy). This roster had neither.

In hindsight, holding on to Terry Rozier was a mistake. The Celtics needed a compliant backup for Irving who could also serve as a confidant, not someone envious of Irving. You can’t have role players who aren’t willing to accept their roles and fancy themselves as a different class of player than they really are. It doesn’t work.

Offensively, Rozier was a nonfactor in these playoffs, shooting 32.2 percent from the field. To his credit, he did accept the role of dogging the opposing ball-handler full-court. But he was never really happy all season.

Fretting about his future payday in restricted free agency, he proved either unwilling or unable to stay in his lane and play his role.

The same was true to some degree with Jayson Tatum and Jaylen Brown, a pair of No. 3 overall picks who entered this season on the cusp of stardom. After being frontmen in the Celtics’ run to the Eastern Conference finals last year without Irving or Hayward, both players struggled to adjust to going back to backup singers for the Kyrie Five. Irving’s tactless criticism of them exacerbated the divide.

While Irving could have offered his criticism in a more artful form, the young guys chafed at any criticism.

“It’s not all Kyrie’s fault,” said a team source. “Those guys don’t like criticism.”

The Celtics felt like a car with too many passengers and a raging disagreement about the desired destination. Multiple people were grappling for control of the steering wheel. Ultimately, no one got control and the car careened through the guardrail.

If Ainge is able to coax Kyrie back, then he has to surround him with a roster more suited to sacrifice for one another, a roster with defined roles that allows Stevens to play Kyrie wrangler. You can’t have a self-centered leader surrounded by self-aggrandizing players. That combustible combination is why the Celtics were a difficult team to coach and a difficult team to embrace.

Ainge put Stevens in a tough spot. However, as Stevens volunteered, this wasn’t his best coaching job. For the first time in his Celtics career, he had a team that had nothing to prove and everything to lose. Unlike prior versions of the Celtics under Stevens, these Celtics crumbled at the first sign of adversity. It’s fitting that the Celtics won their first five games of the playoffs, then lost four straight. It perfectly encapsulates who they were.

“We just didn’t have the fortitude when the tough times hit to push through,” Brown told the media Thursday.

Stevens was never able to really reach this team. He was never able to manage the personalities or placate his star player. The season ended with his star, Irving, taking a page out of LeBron James’s playbook and passive-aggressively overpraising the opposing coach, a not-so-subtle way of making it clear how much he felt his own coaching staff had failed him.

Stevens obviously has a comfort level with Hayward, his former star pupil at Butler, and the Celtics invested heavily in the idea that feeding Hayward minutes throughout the season would allow them to be the best version of themselves in the playoffs. It backfired. Hayward was a ghost, shooting 25.9 percent in the final four games of the Milwaukee series, and the perception that he received preferential treatment from Stevens undermined the coach’s message all season.

We can’t leave out Kyrie. It’s nice that Marcus Smart, who was the real leader of this team, came to Irving’s defense Thursday. Smart said Irving shouldn’t be singled out for the brunt of the blame for the Celtics’ failure to launch after Irving shot 25 for 83 (30.1 percent) in four consecutive losses.

But, as Irving said, this is what he signed up for. That’s how it works when you’re the face of a franchise. Irving has to own this, he has to wear this, he has to accept it, he has to use it to become the player he wants to be. Dodging and ducking responsibility for his primary role in a season gone sideways is conduct unbecoming. He needs to express in blunt terms, like Stevens did, that his performance wasn’t good enough.

You can’t be a leader and hold others accountable if you’re not willing to hold yourself accountable. Playoff Kyrie was a no-show. We care about that, even if he doesn’t.

All of the greats in the NBA have dealt with failure. Larry Bird had to deal with the Celtics’ playoff ousters in 1982 and 1983. Magic Johnson was called “Tragic Johnson” when he struggled in the 1984 NBA Finals. It’s part of the process.

I did a bad job. [Insert Celtics employee here] can say that, from top to bottom.