“I beat myself up about that all the time,” says LeBron James of his impotent fourth-quarter peformances against the Mavericks in last June’s NBA finals. In six games, he averaged just three points in the final period. (Mike Stone/Reuters)

Most of LeBron James’s recent performances have generated gushing superlatives and early discussion of the league’s Most Valuable Player award. Yet even as James puts forth some of the best numbers of his career and fields daily queries about his early-season excellence, his thoughts occasionally wander back to the distress of his fourth-quarter slide against the Dallas Mavericks in the NBA Finals.

Though James’s highlight-show dunks — did you see him catapault over the head and shoulders of the Bulls’ John Lucas III just over a week ago? — have gotten better play, he and the Miami Heat are resolutely taking concrete steps to prevent another mystifying swoon in the playoffs. They have been working to sharpen their fourth-quarter execution, relying in part on a new lineup designed to distribute shots, get defensive stops and thwart an overemphasis on one player’s performance.

Many players bear responsibility for the Heat’s six-game Finals defeat that featured late-game collapses and blown leads, but it was James’s inexplicable ineptitude that attracted the most attention — and excoriation. After averaging 26.0 points per game in the three early playoff rounds, he scored at a 17.8 clip against Dallas and averaged just 3.0 in the fourth quarter.

“I beat myself up about that all the time,” said James, who will lead the Heat against the Washington Wizards Friday night at Verizon Center. “I finished games in the Philly series, in the Boston series, in the Chicago series. Then, I didn’t [finish well] in the Finals and I got a lot of junk about that.

“I understand what this game is about. That was the biggest stage, and I didn’t produce for my team down the stretch. And that hurt me more than anybody, to not be there for my teammates in the big moments. I learned from that, and it’s made me a better person and better player as you see today.”

Indeed, James has placed himself at the forefront of MVP discussion by averaging 28.5 points, 8.2 rebounds and 6.9 assists per game, but Heat Coach Erik Spoelstra understands that playoff victories are often earned not with general brilliance, but with late-game execution.

He said this week that the Heat has improved in the fourth quarter, sharpened more by plain old experience than any strategic design. He says his philosophy on who should take the last shot in a close game hasn’t changed: the guy who is open.

Even so, Miami has gotten an occasional lift from a lineup it envisioned riding to the playoffs last year — but couldn’t utilize during the regular season because of injuries. Spoelstra has lately tasked James with running the point in the fourth quarter while sharing the floor with shooting ace Mike Miller, slashing guard Dwyane Wade, rebound-hungry Udonis Haslem and the increasingly reliable finisher Chris Bosh.

The lineup lacks a true point guard and a true center, but it gives Miami lots of long arms and good size, and an excellent defensive presence. It also takes advantage of James’s massive skill set — he can pass and penetrate with equal facility — at a particularly suitable stage of the game.

Allowing James to run the offense opens up more wide-open chances for his teammates as he inevitably draws double teams. His size, his teammates say, helps him see the open man and deliver crisp passes. Though James insists the role doesn’t deprive him of scoring opportunities, it will have the benefit of providing opportunities for others to perform in the clutch — and perhaps decreasing Miami’s dependence on James for fourth-quarter miracles.

“It’s a great lineup for us . . . in the fourth quarter when it’s time to close out games,” James said. “It’s a lineup that really gives us unique things, especially defensively.”

Though James has tallied more points than any Heat player in the fourth period, his fourth-quarter contributions have made up a smaller percentage (less than 19 percent) of his total points than Bosh, Wade, Miller or Haslem. Miller leads Miami with more than 50 percent of his total production coming in the final period.

“One thing about great teams is they take the shots available,” Miller said. “There are guys who are closers, guys who are finishers, but at the same time, guys who are available have got to step up and make shots.”

And, most Heat players will be quick to add, make a defensive play or grab a rebound, too.

“It’s building the habit throughout the season,” Bosh said. “It’s something you have to be conscious of. Yeah, we came up short in the Finals. We had double-digit leads in the second half in damn near every game. . . . If you just continue to move the ball, have confidence and trust in each other, great things happen.”

In Tuesday’s 107-91 victory over the Cleveland Cavaliers, Miami ran away with the victory after Cleveland had closed to within four early in the fourth quarter. In the waning minutes, James fed Haslem for an easy jumper; Wade and James each sliced through the heart of the defense for pretty scores; and then James finished the onslaught by hitting Haslem for a dunk and Miller for an open three.

James chipped in just four points in the period as Haslem led with 10, but his contributions were huge.

“Even though we have three great players on the floor, you have to utilize all five guys on the floor, especially in the closing moments,” Wade said. “Us three [Wade, Bosh, James], Udonis and Mike, that’ll be an ideal lineup for us. . . . It’s no secret that’s the lineup we want to see out there to close out games.”