Nothing tantalizes the NBA mind more than an under-23 talent who has flashed—or, even better, sustained—superstar production.

Roster a player of that ilk, and everything feels possible for the future. The league's best player may not reside on this list, but one of these players (if not more) will be regarded as such at some point down the line.

Thanks to some impressive draft hauls in recent years, the game looks littered with next-in-lines. But there's a big difference between being an intriguing up-and-comer and a centerpiece-in-training. We're hunting for the latter by using everything from traditional metrics and the trusty eye test to analytics and future projections.

Since the list is confined to players under the age of 23, we'll only include players who haven't celebrated their 23rd birthday by Oct. 17. You'd think that might limit our list of candidates, but it was harder to hold players out than to anoint them with this distinction.

On the Radar but Off the List (For Now)

Deandre Ayton, Phoenix Suns

Ayton's second go-round in the league effectively formed one giant arrow pointing up. His stat sheet climbed nearly across the board, and the eye test validated those numbers. Most importantly, he improved from being a defensive liability to a serviceable stopper at the basket.

Building around him in his current form is tricky since he's neither an interior anchor nor a floor-spacing center. Only a handful of NBA rosters are constructed around centers anymore, and those 5s have more versatility than Ayton has shown. But his production floor (18.2 points and 11.5 rebounds per game) and growth potential make him a must mention in this close-but-not-quite-there category.

Tyler Herro, Miami Heat

The growth in Herro's game inside the bubble was apparent and at times astounding. The blueprint of a go-to perimeter threat is easy to spot thanks to his off-the-dribble shooting, passing creativity and he-can't-really-be-20-years-old fearlessness.

But the Heat had enough depth where he could pick and choose his spots, which created fluctuations on his stat sheet. Would those be ironed out with more responsibilities on his plate? Until that inquiry is answered, it's impossible to consider him an obvious building block.

Jaren Jackson Jr., Memphis Grizzlies

Jackson might be the best Robin on this list, as his combination of shooting, rim-protection and defensive versatility nearly helped push the Grizzlies into the postseason. But teams are built around Batman, and it's not clear Jackson could make that leap if needed.

He's had moments of brilliance—the Beale Street faithful might still be celebrating his clutch step-back triple over LeBron James some two months into his pro career—but consistent star-caliber contributions remain elusive. Based on Jackson's work to date (career 15.5 points, 4.6 rebounds, 1.7 threes and 1.5 blocks per game), he may be likelier to top out as a supporting actor than he is to grow into a leading role.

Michael Porter Jr., Denver Nuggets

It doesn't take much imagination to picture Porter as a walking mismatch. He is, or at least can be, a 6'10" three-level scorer. Defenses already barely bother him, as he averaged 20.4 points per 36 minutes on 50.9/42.2/83.3 shooting as a freshman.

But two stains on his resume prevent him from leading a roster. The first is a frightening injury history highlighted by a back injury that effectively erased his lone season of college hoops and his would-have-been rookie campaign in 2018-19. The other is the defensive lapses and non-scoring question marks that have held him back from a larger role in Denver (16.4 minutes per game).

Luka Doncic, Dallas Mavericks

And the award for least surprising selection goes to...

This hand was already tipped by the lead photo, but even if it wasn't, there would still be zero suspense. The question isn't whether Luka Doncic ranks among the league's best building blocks—it's if he leads that group. Spoiler alert: He does.

"Luka has size and elite playmaking and shooting right this second," a Western Conference executive told ESPN's Tim Bontemps. "He impacts winning. I believe his game is not only sustainable but has the ability to continue to get better."

It's terrifying to think this isn't Doncic's final form. He just joined Oscar Robertson and Russell Westbrook as the only players ever to average 28 points, nine rebounds and eight assists. How much better could Doncic possibly get?

And yet, this was his second NBA season. He's 21 years old. Improvement isn't simply possible—it's inevitable.

De'Aaron Fox, Sacramento Kings

De'Aaron Fox's position in this tier might be the most tenuous since the Sacramento Kings have tried and failed to build a winner around him. But holding the failings of their front office against him—see: drafting Marvin Bagley III over Luka freakin' Doncic—is faulty logic.

In a perfect world, the speedy 6'3" guard would spearhead an attack that operates at ludicrous speed. In reality, Sacramento somehow trudges along at the 12th-slowest pace. Fox would also ideally pair with an explosive pick-and-roll screener. In practice, the Kings' screeners landed just 17th in efficiency.

It's imperative, then, to consider the conditions in which Fox has operated. A lead guard can only do so much without proper weaponry around him, and the Kings haven't delivered on their end of the bargain.

But it's fascinating to think of the possibilities for Fox with a well-maintained roster at his disposal. His elite burst can take him anywhere he wants to travel. Defenders leave themselves a cushion—both to respect his speed and because his outside shot is still developing—and he still cooked them as a 70th-percentile finisher on isolations. Only three players earned more free-throw attempts from drives than Fox's 3.7 per game.

Building around him requires buying into his shooting potential, as that remains his biggest swing skill. But there are several reasons to believe he'll find his touch, including last season's 37.1 three-point percentage and this year's 55.1 percent connection rate from 16 feet to the three-point arc. If he gets to league-average from distance, that's enough for future stardom when considering his elite speed, disruptive defense and playmaking prowess.

Shai Gilgeous-Alexander, Oklahoma City Thunder

The simplest building blocks to work with aren't blocks at all. They're balls of clay that can be molded into whatever shape is needed to fit the project.

That's the primary argument for including Shai Gilgeous-Alexander, who has already changed teams, spent at least 10 percent of his minutes at all three perimeter positions and still ranks as one of the league's top under-23 talents. No matter if his squad needs a go-to scorer, a pass-first lead guard, a spot-up sniper, an off-the-dribble attacker or a versatile defender, he carries every club in his bag.

"He's not great at any one aspect of the game, but he's good at all of them," The Ringer's Jonathan Tjarks wrote. "He doesn't have any defined weaknesses."

Gilgeous-Alexander has orchestrated surprise playoff runs with big scoring forwards on the Los Angeles Clippers and as part of an absurdly efficient three-guard monster with the Oklahoma City Thunder. That's exceptional pliability for a cornerstone since it allows the rest of the roster to take any shape.

As a 22-year-old who hides his non-elite explosion with seamless changes of direction and speed, his skill-based game is built to age gracefully. He may not have a standout skill on the stat sheet yet, but that might only be because his clubs haven't needed that from him. Given his willingness to adapt, it's easy to think he has it in him should the situation demand it.

Ja Morant, Memphis Grizzlies

We all watched Memphis rise from obvious rebuilder to legitimate playoff threat this season, right? Well, Ja Morant's cornerstone credentials should be easy to recognize.

In case anyone needs a refresher—it's been a calendar year since opening night, after all—the Grizzlies lost 49 games last season and then traded away franchise floor general Mike Conley in July. Oddsmakers braced Beale Street for a mountain of losses. Morant ensured they never came.

He dazzled almost immediately—his third professional outing featured 30 points and nine assists—and helped the Grizz get their groove back. By year's end, he was one vote shy of a unanimous Rookie of the Year Award, and Memphis landed one play-in tournament away from the campaign's most improbable postseason trip.

"You forget that he's a rookie, watching him," Conley told CBS Sports' James Herbert in July. "The things he's doing, a lot of guys in this league can't do. And he's doing it at [20] years old, whatever he is. He's special."

Morant is only the seventh rookie to ever average 17 points and seven assists. He's the first freshman floor general to hit those marks while giving away fewer than 3.5 turnovers per game (although turnovers weren't tracked during Oscar Robertson's rookie year). Morant's 3.8 win shares were the sixth-most among all rookie guards in the 2010s.

With sizzle to ignite the fanbase and substance to elevate a supporting cast, he's exactly the kind of lead guard teams would want to build around.

Jayson Tatum, Boston Celtics

Jayson Tatum's place on the hoops hierarchy was tough to pin down ahead of this season.

The third pick of the 2017 draft enjoyed a (relatively) quiet but efficient rookie campaign, but expectations skyrocketed when he handled a starring role for the injury-riddled Boston Celtics in the 2018 postseason. A lot of those hopes were subsequently deflated during a turbulent 2018-19 campaign that ended with a second-round flameout against the Milwaukee Bucks.

But with Kyrie Irving out of Boston and Tatum now in the spotlight, his NBA rank has never been clearer.

While his first half secured his initial entry into the All-Star Game, his second-half surge propelled him to near-superstar heights. More importantly, that transformation carried into the playoffs, where he was one of only three players to average 25 points, 10 rebounds and five assists. Four-time MVP LeBron James and reigning back-to-back MVP Giannis Antetokounmpo were the others.

"He's a superstar," Kemba Walker raved after Tatum's 29-point, 12-rebound, seven-assist effort in Game 7 of the Eastern Conference Semifinals. "... Special, special kid. He works hard. He wants to win. He loves playing with his teammates."

Tatum played the biggest role in the Celtics' fourth-place finish in offensive efficiency and was a major reason why they also ranked fourth at the other end. He's a three-level scorer, a multi-positional stopper and a rapidly improving distributor.

He is, like Walker said, a full-fledged superstar at the age of 22.

Zion Williamson, New Orleans Pelicans

Zion Williamson's game defies gravity.

NBA players don't come with his build. Only three players were listed at higher weights than his 284 pounds; all three are 7-footers (Tacko Fall, Boban Marjanovic and Jusuf Nurkic). Williamson stands just 6'6". The next-heaviest player this season his height or shorter was Golden State Warriors rookie Eric Paschall, who checked in at 255 pounds.

Williamson's frame alone is unique, but it approaches otherworldly territory when combined with his moon-boots bounce. He not only explodes like a jet-pack lift-off, but then he springs into second and third jumps faster than a pogo stick. Before he even hit the NBA hardwood, he was dubbed the league's best athlete in NBA.com's annual survey of general managers.

The focus on his weight isn't entirely tied to amazement, though. There's also a school of thought that he needs to shed some pounds, and if he doesn't, it could limit his longevity. He does have some knee issues in his past, so health is the biggest question for his future.

Of course, it might be the only one.

"If [Zion's] healthy, I think he'll win an MVP," a Western Conference coach told Bontemps. "That's how good I think he is."

Williamson is still learning the game (like all rookies), but that hasn't held back his dominance. He popped for 29.1 points per 36 minutes as a rookie, plus he hit 58.3 percent of his shots and showed some advanced feel for playmaking. If he can stay healthy and better engage on the defensive end, he has as much potential as anyone in the league.

Trae Young, Atlanta Hawks

Trae Young is the worst defender in basketball. That's not a hyperbolic jab; stats say it's the truth. He ranked dead last in ESPN's defensive real plus-minus, which is exactly where he finished 2018-19 too. Defensive box plus/minus is slightly more generous, as he's graded as the second-worst defender the past two campaigns (minimum 100 games).

Admittedly, this is a strange place to start a discussion on why Young is worth building around. But the fact that he offers no more resistance than a wet paper bag and still finds his way onto the list—plus the All-Star roster—says everything you need to know about his offensive excellence.

He bends opposing defenses the same way Stephen Curry did during the Golden State Warriors' dynastic run of three titles in four years. Young isn't the next Curry, of course, but the former delivers a similarly enormous impact.

Young is the kind of shooting threat who must be monitored at all times once he crosses half court. It's not just that he can launch from the logo—it's that he's a pull-up threat from anywhere (2.6 pull-up triples per game) and one of the game's most prolific playmakers (17.3 potential assists per game, second only to LeBron James). His quantifiable influence is silly: Atlanta's offense was 15.5 points better per 100 possessions with him than without.

The defense is concerning, but the right roster can hide a lot of his shortcomings. What teams can't do is create a player nearly as lethal as Young on offense. This was his second season in the league, and he finished it ranked fourth in scoring (29.6) and second in assists (9.3). He is already unstoppable, so it will be incredible to see where the future takes the 22-year-old. Anyone running a front office should want to find out.

All stats courtesy of NBA.com and Basketball Reference unless otherwise noted.

Zach Buckley covers the NBA for Bleacher Report. Follow him on Twitter, @ZachBuckleyNBA.