Cavaliers’ LeBron James is playing at an historic level in NBA Finals

A huge banner is back in place on a building across the street from Quicken Loans Arena, where Huron and Ontario streets combine to form a Y.

It was taken down almost four years ago, when a favorite son punctured the trust of his hometown state and basketball jerseys were burned not far from it. But a similar black-and-white image was put up again after LeBron James left Miami to return to the Cleveland Cavaliers last summer.

You don’t see his face, only the No. 23 on his back and his trademark pre-game talcum toss. The banner is 10 stories tall. It might need to be even bigger.

James is playing larger than ever in the NBA Finals, “so outside the box right now” by his own admission that it’s already historic and the Cavaliers hold a 2-1 lead over the favored Golden State Warriors.

James is averaging 41 points through three games, the most by anyone this early in Finals history, and continues to prop up a team without injured All-Stars Kyrie Irving and Kevin Love.

He has scored, assisted, or created 200 of the Cavaliers’ 291 points, according to Synergy Sports Tech, an immense output for anybody, even James.

“You [ask] how much it’s taken out of me. I want it to take it all,” a bleary-eyed James said Wednesday. “You [media] guys can see I’m not getting much sleep right now but I’m OK with that. Being the sole leader of a team and a franchise, it’s taxing, but I accept the challenge. I accept it all.”

James has no choice if he wants to avoid falling to 2-4 overall in the Finals.

The ragtag Cavaliers crew he’s dragging from game to game would be laughed at by any Hollywood script screener.

There’s the Aussie who went undrafted out of tiny St. Mary’s College, but reporters from his country now wonder if he should be knighted back home for his inspirational playoff run. Let’s call him Matthew Dellavedova. Sure.

And the wild shooter who makes fans stand in anticipation every time he throws up a shot, even if there’s only a minor chance an off-balance, highly contested three-point attempt falls true? His name will be J.R. Smith.

We’ll also give James a defense-minded back-court mate with a retro ‘90s haircut (Iman Shumpert) and a plodding center acquired earlier this year after averaging a single-single for lowly Denver (Timofey Mozgov).

James can’t do anything less than average 47.3 minutes, plus 12 rebounds and 8.3 assists if the Cavaliers want to win. So he does.

There’s something extra driving James but he won’t say what it is. He has cryptically referred to being inspired by a “secret motivation” and again declined to reveal it Wednesday.

He admitted to telling former Miami teammate Dwyane Wade, but Wade “ain’t gonna tell you guys,” James jokingly told media members.

The easiest guess: James is pushing himself for the city of Cleveland, sometimes derisively called the “Mistake by the Lake” because of its pollution history and lack of major pro championships. The have been no Super Bowls, no NBA trophies and World Series rings only twice (1920 and 1948).

Or maybe it’s not so secret.

“It was a bitter moment when I left the first time, but it’s a sweet moment here now that I’m back. Both sides had an opportunity to kind of miss each other,” James said. “I know the fans are excited and exuberant about me being back. Not only just about me — this team, putting this team back in the position where they can compete and have something to talk about.”

One of the main talking points, tied for first with “What happened to the Warriors’ offense?” in this series is whether James can sustain it.

His playing time, spread thickly over three close games, hasn’t affected him in a negative way other than 31.4% shooting accuracy in Game 2.

“He’s doing a good job of being smart when he’s choosing his attack points and when he’s trying to conserve energy,” said Warriors forward Andre Iguodala, given the task of guarding James most of the time. “He’s playing inside, outside, trying to get to the line, mixing it up a little bit. But from our perspective, we’re trying to do the same things — keep throwing bodies at him. Hopefully it will swing our way.”

With so little room for error or injury, the Cavaliers received positive medical reports on two members of James’ support staff.

An MRI exam on Shumpert showed nothing more than a bruised right shoulder, and Dellavedova continued to recover from cramps and dehydration. Both are expected to play Thursday in Game 4, Cleveland Coach David Blatt said.

Dellavedova has turned into Cleveland’s second-best player in the absence of Irving and Love. His 20 points were difference-makers in Game 3 but his 38 minutes were apparently too much. He was at a hospital an hour after the game, an IV in his arm, and carried two cups of fluids as he walked around Wednesday afternoon.

“The tank is low and we’re doing everything we can to fill it back up,” Blatt said.

Two more victories separate the Cavaliers from their first true basketball joy since forming in 1970.

And James from one of the greatest feats in 59 years of the Finals.

mike.bresnahan@latimes.com

Twitter: @Mike_Bresnahan