There is no strict definition of leadership in the NBA, or in any sport. Some lean toward vivid animation and the fiery speech, while others take the measured approach. Today’s focus is on three backcourt stars who have designs on the title — and the remarkable contrasts in style.

It’s pretty simple with Houston’s James Harden. He’ll just take every shot. It does seem that way sometimes, and I’ve always wondered how teammates feel when Harden dribbles out so much of the clock. But who’s to argue with his gaudy scoring outbursts of late, especially with Chris Paul and Clint Capela sidelined? History won’t view the Rockets as a significant powerhouse, but Harden is lodging himself among the all-time greats of individual scoring.

The Celtics’ Kyrie Irving is an engaging fellow with a whimsical bent (his “Uncle Drew” series is a theatrical masterpiece), and there’s no question who takes the big shot on this team. It has to be Irving, who owns the league’s best handle and has a history of long-range shots in the clutch. It’s just that he has no idea how to lead — and it could cost Boston a shot at the NBA Finals.

A few days ago, after a discouraging loss, Irving cited his young teammates’ inexperience as a factor in the loss while speaking of his talent as “something that’s not meant for other people” and heralding “the magnitude of my voice.”

Oh, please. Kenny Smith jumped all over this on TNT, recalling the dignified, lead-by-example stars of his own career. “If someone told me he was ‘the man,’” Smith said, “then, to me, he wasn’t the man.”

Irving seemed to forget that all of these promising young players — Jayson Tatum, Jaylen Brown, Marcus Smart, Terry Rozier — staged a spirited run through last year’s playoffs, gaining valuable experience along the way. It took a Game 7 loss to LeBron James’ Cleveland team to keep them out of the Finals. They couldn’t be more ready for prime time.

Irving eventually apologized, but he couldn’t help going public with a phone call he made to James, all about what it takes to be a conquer-the-world leader — as if the two are somehow equal in that regard. Given that Irving bailed out of Cleveland because he felt James’ presence was too oppressive, the whole gesture seemed phony — and yet another shot at his young teammates.

There are no bad guys in the Celtics’ cast, but as veteran forward Marcus Morris told reporters, “I’d be lying if I said we knew our identity.”

That’s never been the case in Oakland. The Warriors have been Stephen Curry’s team since he engineered the 2014-15 championship and changed the game of basketball along the way. Really, has he ever said the wrong thing? He takes some of the most brazen, improbable shots in NBA history, but do any of them seem like a bad idea?

For some unstoppable scorers, sharing the load with Klay Thompson would be difficult to handle. That was a cakewalk for Curry. He made soul-stirring sacrifices upon the arrival of Kevin Durant, and now he’s the proud, quiet, unassuming yet indispensable leader with DeMarcus Cousins on board. He made sure Cousins got all of the attention against the Clippers on Friday night. And, yet, even in the shadows, Curry finished the night with a team-high 28 points to go with five rebounds, four assists and one turnover.

When Cousins fouled out and returned to the bench to rousing applause, Curry was beaming. He looked like a parent at his kid’s school play. Harden may win his second consecutive MVP award, and Irving surely will dazzle fans right to the end. In the category of pure leadership, Curry stands alone.

Around the NBA

•Scouts look for an “edge” in players, a toughness often developed through severe adversity. They don’t often trust kids who come from cushy backgrounds, figuring they might fold against the forces of intimidation. In a candid conversation, Sacramento’s De’Aaron Fox — one of the most compelling young stars in the league — addressed the issue on Chris Haynes’ “Posted Up” podcast.

Haynes: “I was told you spoke about growing up in a two-parent household, and how some might have viewed that as a negative, or that you may be soft, that you didn’t struggle.”

Fox: “Yeah, both my parents in my house. I didn’t live in the nicest neighborhood, but I didn’t live in a bad neighborhood. Middle class. Man, it doesn’t matter where you come from. Right? I’m a dog on the court. And when we played a ’hood school, there were people surprised, like, I’m goin’ at dudes. That’s how I am. But, yeah, that’s basically what they’re saying. Because you didn’t struggle, you can’t play a certain way on the court. Doesn’t make sense to me.”

•Some may view the Warriors’ two-week trip as a major inconvenience. Broadcaster Jim Barnett is not among them. “I had to laugh when I found out we had six nights in L.A.,” he said, recalling the NBA’s brutal scheduling of years past. During the 1967-68 season, Barnett’s San Diego (later Houston) Rockets twice played five consecutive nights in November, played 13 games during a 16-day stretch in February, then another five in five nights in March.

“It was always too late to fly out after the game, and sometimes we’d have a snowstorm delay and show up in the next city too late to go to the hotel. We’d just go straight to the arena, carrying our own bags,” Barnett said. “We never flew first-class, and we really loved it if we got a Holiday Inn. That was like the Ritz-Carlton to us. But we were in the NBA, you know? We loved it. It was no big deal.”

Bruce Jenkins is a San Francisco Chronicle columnist. Email: bjenkins@sfchronicle.com Twitter: @Bruce_Jenkins1