OAKLAND — In the aftermath last June, Draymond Green made a decision. He would construct a dividing line between the mistake he made and how the effects changed him, a distinction between what he did and what he learned. Green’s outburst and resulting suspension in the NBA Finals contributed heavily to the Golden State Warriors’ collapse, the first domino in the downfall of a 73-win juggernaut. He refused to let it burden him, as if in adherence with a guiding principle.

“I’m a firm believer in, ‘[stuff] happens,’ ” Green said.

The Warriors will return to the NBA Finals armed with the chance to avenge last year’s gagging of a three-games-to-one Finals lead over the Cleveland Cavaliers. No player has more to redeem, perhaps, than Green. An accumulation of offenses, culminating with his slapping LeBron James in the groin, earned Green a suspension in the middle of the series. So much had to happen for the Cavs to win — Steph Curry’s knee ached, James chased down Andre Iguodala, Kyrie Irving canned a preposterous three-pointer. It started with Green watching Game 5 from a baseball stadium.

Green will return to the NBA Finals on Thursday night as a different player, more evolved than transformed. Green has always played on the verge of combustion, quick to antagonize officials, harangue teammates or even ream his own coach in a halftime locker room. The Warriors also relied on all those spasms, his competitive fire providing a counterbalance to the nonchalance of Steph Curry and Klay Thompson. The Warriors came to view Green as a welcome bargain. If you wanted Green’s blazing intelligence and penetrating leadership, you had to accept the eruptions. It was worth it, until it wasn’t.

“You don’t want to take all the Draymond out of Draymond,” said Tom Izzo, who coached Green at Michigan State. “You want to curb it a little bit.”

In response to his Finals suspension, Green has harnessed his passion. He discovered boundaries, maintaining his ferocity without inviting needless punishment. He yells at officials, but not past the point of reason. He stopped kicking opponents in the groin. The Warriors still rely on Green as their emotional bellwether, and Green has found a new measure of stability.

“I carried the lessons that I learned with me, but the actual incident — I mean, I put that behind me a long time ago,” Green said. “The things that it taught me, it’s put me in the position of where I am today. I feel better than I’ve ever felt emotionally, just having my emotions in place than I’ve ever felt.”

The evidence supports Green. Smacking James was only the last straw last year. Had he not accrued so many flagrant fouls in the early rounds of the playoffs, the incident would not have cost him a game. This postseason, he has only one technical foul and no flagrant fouls, placing him a safe distance from a possible suspension.

“I’ve never seen him in a better place emotionally,” Warriors Coach Steve Kerr said Monday. “Still playing with rage, desire and force, but totally under control.”

The play that hovers over these Finals happened in the final minutes of Game 4 last year, as the Warriors held a dominating lead over the Cavaliers. Green set a hard, moving screen on James. His frustration evident as the series was seemingly slipping away, James swung his arm and whacked Green, knocking him to the ground. James stepped over him. They tangled as James rose to his feet, and he smacked James in the groin.

“I’m not sure it was his fault for the way that incident happened, the way LeBron stepped over him,” Izzo said. “I’m not sure many guys would let anybody walk over him like LeBron did.”

Upon review, the NBA ruled Green committed a Flagrant 1 foul. The call pushed Green’s total to four flagrant fouls for the postseason, which meant an automatic one-game suspension. His “sin,” as Izzo put it, had been to accumulate so many harsh fouls earlier.

Green watched Game 5 on television next to General Manager Bob Myers from a suite inside O.Co Coliseum, across the street from Oracle Arena, during an Oakland A’s game. Nearly dead and buried, the Cavaliers beat the Warriors and sent the series back to Cleveland, suddenly revived.

“Your greatest strength can be your greatest weakness,” Cavaliers veteran Richard Jefferson said. “Draymond is a very intelligent player. But for him, he needs to keep his emotions in check. I think our team was the most poised last year. I think that’s why we were able to win the championship.”

During Game 5, Izzo called Green. “Surreal,” he said. He felt he needed to check on a beloved player. Already, Green had started to insist the suspension had not weighed on him.

“I know how much he’s hurting over things like that,” Izzo said. “But he can put on a decent front. It wasn’t like he was feeling sorry for himself. He was still himself — still half mad, still Draymond.”

When Green returned, he almost dragged the Warriors to a championship. His Game 7, forgotten amid Cleveland’s joy and James’s incandescence, would be remembered as an all-time performance had the Warriors won. He scored 32 points on 11-of-15 shooting, snared 15 rebounds and dished nine assists, while quarterbacking Golden State’s defense.

“How many guys could bounce back from that, and have one of the best games of the year?” Izzo said. “I think that tells you the competitor of Draymond Green. That was one of the things I was most proud of him for. He didn’t hang his head. He went out and competed, maybe at a level I’ve never seen him.”

In the offseason, Green recognized the need to control himself, while still being himself. It was not in his nature to castigate himself or to wallow. But he knew he had to mature. When his rage spilled over, it came from a competitive place — he still calls Izzo after the Spartans win or lose, to congratulate or to critique. But he realized it had started to hinder the Warriors.

“All things that happen bad aren’t that bad, when you take a step back and look at them,” Green said. “It’s something that I learned from and will stick with me for the rest of my life. And not the suspension. The lessons that the suspension taught me.”

Green did not overhaul himself. He collected 15 technical fouls in the regular season, a telling number. He still made his point to referees, but remained one shy of an automatic suspension.

“He’s not afraid to hear his own voice,” Izzo said. “I don’t think he’ll ever be the guy that if there’s a question mark at all, he’s not going to say something. He’s never going to be that guy, nor would I want him to be. But he’s not going to beat a dead horse, either. He got better at that.”

This summer, Izzo worried for Green when the Warriors signed Kevin Durant. His scoring and place within the Warriors would likely diminish, but “it mattered none to him,” Izzo said. Green is a singular talent, a player without a set position capable of performing any task. He plays point guard. He protects the rim. He drains three-pointers. His passing often catalyzes the Warriors’ offense. His team defense approaches genius — he knows the perfect moment to rotate on to a helper’s man, and just when to scurry back to his own man. He leaves a massive imprint on every game, even without scoring in double figures.

“I don’t know how he’s blocking shots,” Izzo said. “He’s too slow, he can’t jump, but he’s blocking shots. As he grows and matures, which he is doing, I think he could be one of the more unique and elite players that maybe ever played the game. That’s a big statement. Magic Johnson came out of our school.”

Green will have an opportunity to burnish his standing in these Finals. He will use what he learned last year, even as he shoves aside what caused the lesson.