LeBron James’ decision to leave Miami and go home is the kind of seismic shift and watershed moment that doesn’t come around very often in the NBA.

Ask yourself, what other MVP winner, with multiple awards, who had won at least one title decided to leave his team when he was still in his prime?

You have to go back to the mid-1970s, when the Bucks reluctantly traded away an unhappy Kareem Abdul-Jabbar to the Lakers to find the last time the NBA’s No. 1 superstar moved to a new team before his 30th birthday.

James has four MVPs, two titles and turns 30 in December. Abdul-Jabbar had three MVPs, one title and was 28 when the Bucks sent him off in June 1975, in a multi-player deal.

James admitted the Cavaliers were “not ready right now. No way … It will be a long process, much longer than it was in 2010.” So who knows when he’ll win his third ring? This move might be dicey, from that standpoint. But as far as Abdul-Jabbar is concerned, he prospered with the Lakers as he went on to win five more times.

Since he left Milwaukee, the Bucks haven’t sniffed an NBA Finals and there hasn’t been a player considered the best on the planet to pick up and move, although Moses Malone did have two MVPs when he was traded by Houston to Philadelphia in September 1982. Then that season, Malone won his one and only ring by leading the Sixers to the title and also securing his third MVP award. He was 28.

Otherwise, the game’s transcendent stars almost always stay with the teams they’ve won with. The people that lose them find themselves walking around in a stupor for a few weeks, if not longer.

Miami owner Micky Arison had a reaction one would expect, admitting he was “shocked and disappointed” by James’ departure. “However I will never forget what LeBron brought us for four years. Thanks for the memories.”

Arison had better cherish those because the future isn’t looking very good. To even think the Heat, even with Chris Bosh back in the fold to the tune of $118 million over five years, might ever again get to four straight Finals or win back-to-back titles is what Pat Riley would call “a pipe dream.”

The last time a team lost a player of James’ magnitude was when Orlando saw Shaquille O’Neal skip town as a free agent for the Lakers in 1996. But he wasn’t nearly as accomplished. Still only 24, Shaq was still four years away from his one and only MVP award and the first of his four titles.

It was one long road back for the Magic, as it took them 14 years to return to a Finals, with Dwight Howard.

Figure the Heat will be down for quite a while, if not longer.

L.A. FLIP FLOP

During Donald Sterling’s trial this past week, one of the banned Clipper owner’s attorneys, Gary Ruttenberg, slipped up by calling the Clippers the Lakers. Then Ruttenberg joked to the court, “These days you’d rather have the Clippers.”

Believe it or not, you would.

The Lakers can’t seem to do anything right. Even with cap space that could reach $28 million this summer, they couldn’t get a face-to-face meeting with James after they were one of five teams to talk to his agent, Rich Paul. They aren’t getting Carmelo Anthony, even if he’s Kobe Bryant’s surrogate little brother.

This has to be a huge comedown for the NBA’s glamor franchise.

The only move they’ve made — acquiring Jeremy Lin — was to open more cap space for the future and to also get a No. 1 draft pick from Houston that might not turn out to be so great.

“God forbid we end up with absolutely nothing, it’s not for a lack of effort,” Bryant said this past week at his camp in Santa Barbara. “That’s something I would be extremely proud of. We put forth the effort and gave it our best shot. What can you do? You just go from there and do your best and try to win.”

Huh? It sounds like Bryant is playing for just another franchise and not one of the most storied teams in league history.

Normally, you can count on the Lakers to at least be in contention to get the best player in the sport, as they did with Shaq’s arrival 18 years ago. They just chalk it up to who they are and the 10 titles they’ve won since 1980, in addition to their six other Finals appearances in that time. Nobody has their history of success over the last 34 seasons and no team can boast their brand. But now, they can’t even get a sit-down with the game’s No. 1 player.

Plus, they probably have seen the last of Pau Gasol, with the Spurs and Bulls said to be the front-runners as the weekend started. There was some sentiment in the organization to bring back Gasol so the Lakers at least could be respectable and maybe grab one of the last playoffs spots in the West.

That’s not exactly Showtime, any way you look at it.

FROM GLEN TO GM

The way Memphis executives have been talking up former Knicks president and Glen Grunwald, it sure seems like he’ll soon be hired as Grizzlies GM and succeed interim executive Chris Wallace. But you never know about the Grizzlies, with neophytes running interference for the enigmatic owner Robert Pera. … The NBA made $4.522 billion this past season, so let’s not hear the 30 owners plead poverty anytime soon. They’re allowed to do that in 2017 when the CBA will be up for renewal and they’ll be looking for the usual “roll-backs” from players. … Indiana is among the teams that definitely have interest in bringing in Carlos Boozer if he’s waived by the Bulls via the amnesty provision. The Pacers would love to make a deal for Phoenix’s Goran Dragic, with Lance Stephenson being a candidate to go to the Suns in a sign-and-trade. But the Pacers want to keep George Hill, their much-maligned point guard. Stephenson is more likely to land in Charlotte which will have to overpay him at about $12M per year.

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SLAM DUNKS…

— In his announcement that he’s going home, Lebron James mentioned Kyrie Irving, Dion Waiters, Tristan Thompson and Anderson Varejao by name. Missing from the list of his new teammates: Andrew Wiggins, the No. 1 overall pick in June, who has been mentioned as trade bait to bring Kevin Love to Cleveland, and Anthony Bennett. Minnesota is demanding Wiggins, but the Cavs are saying he’s not going anywhere. Expect that to change. Love always has wanted to get to a major market (New York or L.A.), but he’s said to be changing his thinking and would go to Cleveland. Ya think?

— The greatest mystery of free agency wasn’t James’ destination, but why Charlotte signed Gordon Hayward to a four-year, $64-million deal when he’s averaged all of 12 ppg in four NBA seasons and his shooting percentage has dropped each season, from 49 to 46 to 44 to 41% last season. The second-greatest mystery of free agency why the Jazz matched the Hornets’ offer sheet, bringing him back at $16 mil per when he’s worth maybe half of that. That’s Utah’s plan, an absolute cap-killer if there ever was one.

— Chris Bosh made out by accepting Miami’s $118-million deal, scoring $30 million more than if he had taken the Rockets’ four-year package. The Heat is looking to lock up Dwyane Wade at a smaller number… Oklahoma City’s Jeremy Lamb, once considered the Thunder’s rising star and a viable replacement for James Harden, is starting to look like a bust. He shot 32% at the Orlando summer league. By now, he shouldn’t even be playing in the summer circuit.