LeBron James walked slowly up the court on the Dallas Mavericks’ last possession, not bothering to give chase as the painful final seconds ticked away. When the buzzer sounded, James sought out Dwyane Wade as the Mavericks began celebrating the NBA title they earned with their 105-95 victory in Game 6 of the NBA Finals. James and Wade shared a brief, even half-hearted hug.

James looked eager to get off Miami’s home court at American Airlines Arena. With his head down, jersey hanging out of his shorts, James beelined to the tunnel to the locker rooms. James finished with 21 points to lead the Heat, including seven in the fourth quarter. It was his best performance of a series in which he will be remembered more for what he failed to do than what he achieved. It might be a six-game effort that will define him for a long time.

 “It hurts, of course, but I’m not going to hang my head low,” James said. “You can never hang your head low when you know how much work you put into the game of basketball when the lights are off and the cameras aren’t on.”

Eleven months after James talked about winning multiple NBA titles during a much-derided celebratory fan event in this arena shortly after he, Chris Bosh and Wade signed with the Heat, James not only failed to win, but also to meet expectations. The series defeat came four years after James watched the San Antonio Spurs celebrate an NBA title on the home court of his former team, the Cleveland Cavaliers.

“Anytime you feel like you get to the top of the mountain, and you fall off, it’s definitely a personal failure,” James said. I “got close. I won two more games than I did in ’07. Hopefully, the next time I get here, I’ll win two more games than I did in ’11.”

James was largely ineffective Sunday after hitting his first four shots and scoring nine points in the first five minutes. He hit three of five field goals in the fourth quarter, but he committed a crucial late turnover — one of his game-high six — while repeatedly passing up shots. Throughout the series, he seemed more eager to distribute the ball than shoot it.

“They did a great job,” he said. “Every time I drove, they brought another extra defender in front of me. They did a great job defensively. . . . I pretty much don’t listen to what everybody has to say about me or my game or what I’ve done with my career. I don’t get involved in that. . . . It doesn’t weigh on me at all.

“The only thing that weighs on me is when I don’t perform well for my teammates and the guys that I play for every day. That’s the only thing that weighs on me.”

Throughout the Finals, he totaled 18 points in six fourth quarters. He scored a career-low of eight points in Game 4 and averaged just 17.8 points overall. After pulling out repeated late-game heroics in Miami’s Eastern Conference finals series against the Chicago Bulls, James contributed few late shots against the Mavericks, let alone game-saving ones.

“LeBron James has been a lightning rod for a lot of everything, criticism and a lot of noise that’s been created outside,” Miami Coach Erik Spoelstra said. “I think it’s really unfair. He made a tremendous sacrifice to come here and he’s been the ultimate team player. He should not be criticized for that.”

James did not help himself by playing along after Thursday’s shootaround when Wade feigned a cough in front of television cameras, joking that he was sick — a gesture interpreted as making fun of Dallas star Dirk Nowitzki, who played Game 4 with a fever. James pulled his jersey over his mouth, smiling and pretending to cough along with Wade.

“They have the incident with the camera and coughing and all that stuff,” Dallas Coach Rick Carlisle said. “You get to Game 5, Game 6, and it becomes personal. Our guys took it personally tonight.”

Carlisle noted that this never turned into a “high-flying” series and that his team represented what the game “should stand for.”

James opened the night looking ready to live up to the tweet he sent before Miami’s Game 5 loss in Dallas Thursday — “Now or never!”

He opened the scoring with a three-pointer. He followed that with a layup on Miami’s next possession. He hit a couple of jump shots to boost the Heat to an early 14-10 lead. He didn’t score again until 3 minutes 56 seconds remained in the second quarter, then went largely dry again until he hit a layup with 1:49 left in the third.

Miami, which trailed 81-72 going into the fourth quarter, got to within four early in the fourth quarter but Dallas pulled away after that.

“Come on, how often do we have to hear about the LeBron James reality show, what he is or is not doing?” Carlisle said. “When are people going to talk about the purity of our game and what these guys accomplished? . . . I’m so proud of what our team stood for. I kept having people come up to me in the last three or four days [and saying], ‘Hey, there’s billions of people rooting for you guys,’ . . . and we could feel it.”