Jermaine O’Neal has known Kevin Garnett for a long time, just about half his life from their days as high school players in South Carolina. He has seen Garnett work himself into such a frenzy that he actually needs to talk himself down.

He has been on the other side of that emotional cyclone and he has seen it up close as a teammate. To O’Neal, Garnett is not that hard to figure out.

“It’s exactly what you see,” he said. “It’s rabid, high emotion. Blood flowing. It is exactly how it looks. He’s a guy that really gets to the limit. Sometimes he has to bring himself down. But, we as a team build off that.”

It was suggested to O’Neal that to some people, Garnett’s particular brand of crazy – KG unplugged, if you will – comes across as phony or fake. 

“It’s real,” O’Neal said. “You know, I’m sure for people it’s hard to gauge because they think it’s for TV. But he is like that all the time. I mean, every day. His conversations are so animated. He’s like that and the thing is, he’s always been like that. I think he needs that to really get his motor going.”

O’Neal paused before leaving the Celtics locker room after a long day and night. “It’s real.”

There’s a new referendum on Garnett, although it’s really the continuation of an old story. On the basketball court, there are times when he slips off that emotional edge and veers into more dangerous territory. Some call him a bully. Others call him worse. It’s a well-worn reputation that arrived with him from Minnesota.

Since coming to Boston, Garnett has done little to change that perception. He taunted Jose Calderon to the point of absurdity, barked like a dog at Jerryd Bayless in an incident that just felt plain weird and got suspended for throwing a wild elbow at Quentin Richardson during the playoffs.

On Wednesday night against the Bucks, Garnett charged down the lane with all the speed of a sprinter and threw down a vicious dunk with the ferocity of a middle linebacker. It was a play that seemed pulled from a time capsule. Vintage KG.

Then he got tangled up with Andrew Bogut, with whom he has battled in the past. Garnett threw an elbow that missed. Bogut responded with a shove that didn’t. Garnett put his hands up and walked away.

It was all there in that one moment. The dunk, the elbow, the retaliation and either the acknowledgment that it went to a place he never wanted to actually go or the understanding that he needed to pull himself back from the edge.

How you feel about that play probably describes how you felt when it came out that Garnett said something to Charlie Villanueva that Villanueva heard to be a personal cheap shot.

“KG called me a cancer patient,” Villanueva wrote on Twitter.

He also wrote this:

“KG talks a lot of crap, he’s prob never been in a fight, I would love to get in a ring with him, I will expose him”

It took Garnett several hours to respond, but he did in a statement that read, in part: “My comment to Charlie Villanueva was in fact, ‘You are cancerous to your team and our league.’”

Villanueva disagreed, telling reporters in Detroit, “I know what I heard.” 

So, there it is. A he said, he said without an ending and entirely open for debate, which is very much in keeping with Garnett’s entire career.

Garnett doesn’t do Twitter, but if he had been online Wednesday he would have seen his whole career laid out and examined in the span of several hours. First, he was an inconsiderate, tasteless jerk. Then he became an aggrieved party, wronged by a man who shouldn’t have broken a code of silence among players.

When his statement came out, it came back full circle and then swung over to the other side again.

To his supporters, Garnett gets himself into such a state that his mind leaves his body in such a way as to invite loud howls and an incomprehensible running soliloquy that is only understood by small woodland creatures and, apparently, Charlie Villanueva. It’s his fuel and also what makes him great.

“I’m a passionate player,” Garnett said. “With all these rules I’m trying my best to get out of situations. I’m definitely not trying to invite them. The game is passionate and I play with a lot of energy for the 15, going on 16 years I’ve played this way. If you like my style that’s what you’re going to love about me. I leave it out there 100 percent on the court.”

To his detractors, that’s nonsense. A convenient cover for a career filled with cheap theatrics in place of meaningful confrontations. 

Others defend Garnett on the grounds that Villanueva should have handled his business like a man, and kept it on the court.

“What I don’t like is the whole Tweeting thing,” Rivers said. “I’ll state that as well. Guys talk on the court. It doesn’t mean they should or shouldn’t. The fact that we’re talking about this is just silly. I used to play and I can’t imagine us running and talking about what was said.” Then he joked, “Larry [Bird] has said some terrible things to me and I’m still hurt by them.”

Whether Villanueva broke some unwritten code among NBA players is really beside the point. That’s Villanueva’s problem. This is really about Garnett and how he conducts himself on the court.

The ironic thing about Garnett’s performance over the years is that for all the chest beating he is also one of the best examples of a selfless superstar the league has seen. He doesn’t care about points, shots or numbers of any kind beyond the final ones on the scoreboard. He’s a brilliant tactician on defense and the heart and soul of one of the best units of the last 10 years.

Of course there are those who will argue that Garnett covers his fear of late-game scoring responsibilities by cloaking himself in a team-first identity. On and on it goes with Garnett, a player for whom there is very little middle ground.

“I’m a competitive human being,” Garnett said. “When I hit the floor I have no excuses for what I’m out there doing. I try to give my team an edge and do it in the right manner, but it’s a contact sport too. Control is a mental thing. I got it.”