Christmas has long been the marquee day of the NBA regular season. The slate of games showcases the league’s best teams and brightest stars and franchises.

The Christmas slate is also one of the biggest narrative drivers of the year. And those who tuned in to the Lakers during their 124-115 blowout loss to the Mavericks in Dallas on Sunday witnessed a tragic reminder of the manner in which James’ Hall of Fame career appears to be ending in Los Angeles.

James scored 38 points (on 13-for-23 shooting) against Dallas, one shy of his season-high set against the Spurs on Nov. 26, adding six rebounds and five assists in his record-breaking 17th Christmas Day game. When he checked out at the 2:32 mark of the fourth quarter, the Lakers were plus-2 in the 34 minutes he played and minus-18 in the 12 minutes he sat.

Individual plus-minus isn’t always reflective of the story of a game, but in this case, it was.

Without Anthony Davis, who is out indefinitely with a stress injury in his right foot, the Lakers simply don’t have much of a chance when James is off the floor. They have lost four straight games — allowing at least 124 points in each loss — and are 1-4 since Davis’ injury, dropping to 13-20 overall and 13th in the West.

The final score wasn’t indicative of how close the game actually was for much of the second half. And with four more games left on their five-game road trip, they are in jeopardy of plummeting further down the standings.

When asked if he believes the Lakers are resilient enough to climb out of their predicament, James offered a bluntly candid assessment.

“I think I look at it that way,” James said. “I look at it the other way, too, like, how many times are you going to try to dig yourselves out until it’s too much dirt on you?”

James, who has occasionally voiced concerns with the roster throughout the season, has become increasingly critical in recent postgames sessions since Davis’ injury.

“Reality is, without AD, we lose a lot of length, which we don’t have already,” James said. “So we have to make up in ways that, without AD, is very difficult, very challenging. So, I think at one point we had a lineup of I think (Austin Reaves) was the tallest guy on the court. So, you don’t have to be a rocket scientist to figure it out.”

James has been direct about the team’s lack of shooting and size. There’s been subtle jabs at the team’s collective talent as well. The subtext to his messaging, of course, is that the Lakers’ roster could benefit from a much-need upgrade from the front office via a trade (or two). And it’s difficult to disagree with James’ judgment or his application of pressure.

After a slowish start, James is surely doing his part, scoring 30-plus in seven consecutive games, the longest active streak in the NBA.

He continues to break and set records with an unprecedented longevity. Among many notable examples to choose from this season, he has already passed Magic Johnson in career assists, and will likely pass Kareem Abdul-Jabbar on the all-time scoring list within the next month and a half.

But James’ 20th season, much like his 19th, is essentially being wasted on a seemingly lottery-bound Lakers squad. There have been glimmers of optimism, but like last season, the team has largely underachieved relative to the expectations set forth in the first two seasons of the James-Davis partnership.

Lakers coach Darvin Ham, who trends glass-half-full in most instances, acknowledged the “tough circumstances” James, in particular, is facing amid the team’s struggles.

“Phenomenal,” Ham said of James’ play. “My hat’s off to him. He competed his ass off. It’s tough times right now, tough circumstances. But at the end of the day, you know, we just have to keep mashing forward. He’s the prime example of that. Just his ability to come out game after game after game and put up the type of performances he’s putting up, really try to coach and teach guys in the process of being in the floor, playing with them. Throwing ideas our way. Allowing himself to be coached.

“A lot of guys in that position, everyone doesn’t allow themselves to be coached. My hat’s off to him. His leadership has been showing.”

The game started in an encouraging manner for the Lakers. They doubled Luka Dončić, limiting his offensive output and forcing the rest of the Mavericks to try to beat them. Dallas shooters bricked open look after open look, air-balling several of them. The Lakers played with fire and got away with it. They led 54-43, rotating fairly well and corralling the Mavericks’ offense, for the most part.

But the third quarter, which has been the Lakers’ worst quarter this season, featured a volcanic eruption of historic proportions. Dallas scored 51 points, the highest-scoring quarter on Christmas in NBA history and a league-best mark this season.

Dončić (32 points, nine rebounds, nine assists) picked them apart from the post, Tim Hardaway Jr. (16 of his 26 points in the quarter) drilled several 3s and Christian Wood (30 points, career-high seven assists) dominated in the paint as a roller, passer and offensive rebounder. Dallas made nine of 13 3s in the quarter, shooting 72 percent overall.

The Lakers unraveled, as they often have in second halves and critical moments this season. Within 12 minutes, they went from up 11 points to down 19.

“They countered what we were doing at halftime,” James said. “We didn’t make the proper adjustments once they made their adjustments.”

Part of the remarkable run stemmed from Dončić’s brilliance and the impossible problems he contorts a defense into facing. The Mavericks have loaded their roster with shooting to complement Dončić’s style of play.

“If you see the same coverage over and over and over, at some point you’ll figure it out when you have a high basketball I.Q. Which Luka has, obviously,” said James, who referenced the team’s lack of second-half adjustments multiple times.

But a large part of the Mavericks’ success also came from the fact that the Lakers’ supporting cast is largely unreliable — and there aren’t many players that Ham trusts that are larger than 6-foot-5.

Ham continues to deploy the 6-foot-1 Patrick Beverley alongside the 6-foot-1 Dennis Schröder as the starting backcourt, a combination that just hasn’t worked. The Lakers are already undersized, but Ham tends to favor his smaller players in an attempt to stop the bleeding, even if it yields too many offensive rebounds and easy points in the paint.

One such extreme was when Ham used Westbrook (6-foot-3) at center, along with Reaves (6-foot-5), Lonnie Walker IV (6-foot-4), Schröder and Beverley. That is likely the smallest lineup any team has used this season. The group went -1 in roughly two minutes in the fourth quarter.

“You throw everything up against the wall and see what sticks,” Ham said. “It’s one of those types of situations. AD’s not here, not in the lineup. We’re not going to start using that as an excuse. Hell yeah, it’s a big hole in our lineup. But now, we’re pros. We’ve got to step up.”

Regardless of the circumstance, Ham has maintained a confident exterior. To him, there is always something more the coaching staff or players can be doing to fix things.

But James’ patience seems to be wearing thin as the clock winds down on his legendary battle with Father Time.

This season, James is averaging 27.8 points — 0.4 more than Davis — on 49.6 percent shooting, along with 8.1 rebounds and 6.6 assists. He’s doing so in 36.1 minutes per game — tied for the 14th-most in the league. For reference, Kobe Bryant averaged 28.2 minutes per game in his 20th season. Abdul-Jabbar averaged 22.9 minutes in his 20th. Vince Carter averaged 17.7 minutes in his.

Basically, James is in unprecedented territory not only with his production but his workload as well.

It’s difficult to bet against James with the way he’s defied traditional athlete aging, but at some point, the toll inevitably will affect him. If Davis misses several more weeks, the increased burden that will be needed to withstand his absence is too much to place on James, who will be turning 38 on Dec. 30. There just isn’t another star player or grand adjustment for Ham to turn to.

Reinforcements via trade would obviously help, and the Lakers are still evaluating their options on a dormant trade market. At the same time, it becomes increasingly challenging to justify trading a first-round pick if the group continues to struggle. The front office doesn’t want to compound its previous mistakes with more win-now moves.

There are many slices of the blame pie to be shared. Among them, James obviously bears some blame for part of the roster construction considering his notable input — like supporting the Westbrook trade — he’s had over the past few seasons.

It’s just tough to watch one of the game’s greatest players, with so much greatness still left in the tank, go out with a whimper instead of a bang.

“At the end of the day, I love to play the game of basketball,” James said about how this year has been for him. “I’m still enjoying going out there and playing in front of fans, either at home or on the road. And I’m just trying to control what I can control.

“I show up, try to lead these guys and try to lead to victories and obviously there’s been times when it’s been frustrating. There’s been times that I’ve been happy. There’s been times where I’ve been like, ‘OK, we can do better here,’ or whatever the case may be. But I always try to stay even-keeled.”

(Photo of LeBron James: Jerome Miron / USA Today)