Ranking Zion Williamson, Ja Morant and other NBA rookies by future star potential

Zion Williamson or Ja Morant?

This time a year ago, many of the NBA's rookies were preparing for March Madness. Now, having demonstrated how their games will -- or in other cases won't -- translate to the NBA, we know a lot more about their potential for long-term success.

Taking into account what they've seen so far this season, ESPN insiders Mike Schmitz and Kevin Pelton rank this season's rookies by long-term outlook. That means making the cases for Williamson and Morant and figuring out how to handle teenagers who have struggled during their NBA debuts, versus more experienced first-year players who have contributed immediately.

Note: Find each writer's top-10 rankings at the bottom of this article.

More: Ranking the 25 best NBA players under age 25

Zion all the way, or a case for Ja?

Pelton: It's no surprise that this season's top two picks have separated themselves from the field. Since making his delayed debut following knee surgery, Williamson has been dominant. As we wrote about after the All-Star break, Zion has scored with both high volume and high efficiency, helping propel the New Orleans Pelicans back into the playoff race.

Meanwhile, Morant's precocious play at point guard is one reason the Memphis Grizzlies currently hold the eighth and final spot in the Western Conference playoff picture.

Ja and Zion were the lone 2019 draft picks to crack our recent rankings of the NBA's best young talent, where we voted along with our colleague Bobby Marks, with Williamson at No. 2 on the list and Morant at No. 7.

Mike, do you think there's a case for ranking Ja ahead? Or is Zion clearly the best long-term prospect of this group?

Schmitz: Health permitting, Zion is clearly the best long-term prospect of this group. The fact that he has been so productive this quickly while still having so many areas to improve is nothing short of remarkable. I'm still waiting for him to recapture the same defensive motor he showed at Duke, but if he's ever able to turn into a semi-reliable 3-point shooter and fully tap into the playmaking and mismatch shot creation he has shown glimpses of, we're talking about an MVP-caliber player down the line.

That's not to say Morant isn't special in his own right. I ranked him fourth in our 25-under-25 list, ahead of Trae Young, Ben Simmons, Karl-Anthony Towns and Donovan Mitchell, among other already established stars. Morant has all the ingredients to blossom into the NBA's top lead guard in time thanks to his rare blend of effortless explosiveness, creativity with the ball, touch and never-ending confidence.

But when he's right physically, there's only one Zion. He's a force to be reckoned with and possesses the tools to impact the game all over the floor, should he ever buy into the defensive end.

KP, would you agree, or is the race closer than it's made out to be? Who comes next in your rankings?

Pelton: If anything, I see a larger gap between this season's top two players. Morant was one of our biggest top 25 under 25 sources of disagreement, as, much to the consternation of Grizzlies fans, I had him 12th on my ballot.

I'd say I probably lean a bit more toward proven production than peak upside in my assessments, and while Morant has shown his floor is remarkably high for a rookie point guard, much of his efficiency has been built on 37% 3-point shooting that might not be sustainable in the short term. (Morant shot just 36% from the shorter NCAA 3-point line last season.)

Additionally, I think he's probably getting a bit too much credit for Memphis' success when advanced statistics (both box score and lineup-based) show the Grizzlies have exceeded expectations largely because of their strong bench -- more on one of those contributors to come.

Make no mistake, Ja's future is still bright, but even with concerns about Zion's ability to stay healthy, I think he's the clear choice.

Next-best rookie not a 2019 draft pick?

Pelton: I mentioned earlier that Williamson and Morant were the lone 2019 draft picks to appear in our top 25, but they weren't the lone rookies because 2018 lottery pick Michael Porter Jr. cracked the list at No. 23. At the risk of reopening the tiresome debate over what constitutes a rookie, we've always considered all players during their debut season, and of that group, I think Porter is comfortably the best prospect remaining.

Playing limited minutes on a contending team after missing his first NBA campaign following back surgery, Porter has been incredibly productive. He's averaging 19.4 points and 10.7 rebounds per 36 minutes while making a remarkable 54% of his 2s and 42% of 3s.

It's time to see more from Porter defensively -- the biggest reason Denver Nuggets coach Michael Malone hasn't trusted him with larger responsibilities -- and there's a risk of recurrence with his back injury, but that kind of offensive skill explains why he was considered perhaps the best 2018 prospect before he went down.

Mike, would you take any 2019 draft pick over Porter right now?

Schmitz: I also have Porter firmly slotted at No. 3.

While we had MPJ No. 1 on our 2018 mock draft at one point, I wasn't quite as high on him as most were heading into draft night. The injury history worried me, the intel on him at Missouri was spotty, and he tended to play a catch-and-hold, isolation-heavy brand of basketball that often iced out teammates. On top of that, defense was optional and he was such an upright mover on that end.

That said, I've come back around on the 21-year-old, as his talent is simply too clear to ignore, and because of that, he headlined our "Rookies to Outplay Their Draft Slot" piece heading into the season.

As you know, it's not easy to find mobile 6-foot-11 forwards who can shoot it on the move the way Porter can, making him a threat out of a variety of different quick actions. He's just scratching the surface of what he can become, as the majority of his offense is coming off of spot-ups, transition lane-fills, off-ball dives to the rim and putbacks.

While I do think learning to play off of other established players and being pushed to defend is huge for his long-term development, there's also a lot more to Porter's game that probably will become more evident as he gains a longer leash down the road. Although he's no stranger to living off of tough, contested jump shots, he can develop into a lethal mid-post scorer with his ability to rise over the top, and has always had an extremely polished isolation scoring package.

I'm not sure he'll ever be the most in-tune defender or a gifted passer, but he could certainly turn into one of the league's more prolific scorers at a combo forward spot every team is dying to fill.

This is where things kind of open up for me. KP, do you see a significant drop-off here, and who are you looking at next?

Potential or production?

Pelton: So this is where I think we encounter two distinct groups of players who are challenging to compare to one another. Besides the three players we've mentioned, the most valuable rookies by advanced stats have almost exclusively been age 22 or older: Brandon Clarke, Terence Davis, Kendrick Nunn (who went undrafted in 2018 before playing his first season in the G League) and Matisse Thybulle.

At the other end of the spectrum, you've got lottery picks who have been slow to help their teams in terms of winning and losing: RJ Barrett, Jarrett Culver, Darius Garland, Rui Hachimura, De'Andre Hunter and Cam Reddish. Of them, only Hunter is older than 21. (I'd put the other two top-10 picks, Jaxson Hayes and Coby White, somewhere in between those extremes along with Tyler Herro.)

As I mentioned earlier, I tend to favor high-floor prospects over high-ceiling ones, so I would probably round out my top five with Clarke and White before getting to any of the other top-six picks. How about you?

Schmitz: No question. It seems this season those two groups are as distinct as ever. The success of more veteran rookies does seem to be a trend in recent years, and I think it has led NBA scouts to start straying away from the raw "swing" prospects who might not pan out until they're on to their next franchise. Undrafted success stories Duncan Robinson, Fred VanVleet, Nunn and Davis and even second-rounders like Cody Martin and Devonte' Graham have somewhat altered the way scouts are viewing the draft.

That bodes well for proven players in this year's draft like Payton Pritchard, Skylar Mays and Cassius Winston, among others.

With that said, I still tend to lean more toward long-term potential with these rankings, almost to a fault, as you'll see by my top-10 list.

Some of that is simply a function of our job. We spend so much time evaluating the elite youth prospects like Barrett, Garland and Reddish from about age 15, which makes it tougher to move off of our own draft-day rankings or evaluations. Although I'm well aware that a 50-plus-game NBA sample is often more indicative of a future NBA career than any collegiate or EYBL stats, I tend to be more cautious in writing off struggling rookies.

So it should come as little surprise that I have Barrett slotted fourth despite what has been an underwhelming rookie season relative to expectations. His woeful 47.4% true shooting percentage is cause for concern, and I'm not sure how much light there is at the end of the tunnel in the Big Apple. Still, the 19-year-old has started to turn the corner, averaging 17.8 points, 4.0 rebounds and 3.6 assists in 29.1 minutes over his past five games while shooting 51% from 2 and 42.9% from 3.

The Knicks have one of the worst-shooting rosters in the NBA, and it shouldn't have been a shocker that an aggressive slasher such as Barrett struggled out of the gates on a clogged floor. While he'll need to prove he can stabilize as a shooter, improve around the rim as a finisher and continue to fine-tune his decision-making, I'll bet on the 6-foot-7 Barrett, who is one of the most accomplished youth prospects in recent memory. If Leon Rose can somehow find a way to put some shooting around him and add a big point guard like LaMelo Ball in the draft, Barrett's outlook would change drastically.

As for my fifth prospect, I'm still rolling with Garland, whom I ranked fourth heading into draft night. While I'm well aware he has gone through major growing pains this season and I imagine he's not even on your top-10 list, I think it's important to remember this is basically his freshman year of college after playing only five games at Vanderbilt. He dealt with injuries in training camp, was out of shape and has yet to get fully comfortable.

But I've long been a huge believer in Garland's skill set, and guards who can shoot off the bounce with range, change speeds and direction on a dime, facilitate off a live dribble and drop in floaters have a lot of value in today's game, even if he's likely to always struggle defensively.

KP, what does the rest of your top 10 look like? What were some of your toughest omissions?

Pelton: I think the interesting question, and one that's more art than science, is when to dramatically change one's pre-draft rankings.

I ended up with Garland third in my subjective rankings, one spot ahead of Barrett, but I'm more worried about Garland's long-term outlook because his issues seem to be more physical than skill-based. Garland is just so small that in addition to defense, he also has struggled around the rim, making a league-low 44% of his shots in the restricted area (minimum 100 attempts, per NBA Advanced Stats). Improved skill can help Garland become a contributor, but his size puts a cap on his potential, so you're right that I wouldn't have him in my top 10.

I'm more hopeful that Barrett's struggles are partially situational, though they're certainly of a piece with the concerns about his game entering the league. I'd slot him sixth, with Herro seventh, Reddish eighth (as his efficiency has come on over the course of the season, though the full-season numbers offer a better guide to his future outlook than the recent splits), Thybulle ninth and round out my top 10 with Davis.

Besides the players we've mentioned, a few others I considered include Lu Dort (shooting 36% on 3s as a starter while playing elite perimeter defense at age 20), Sekou Doumbouya (extremely inefficient this season but getting minutes as the league's youngest player) and Kevin Porter Jr. (playing well for a 19-year-old project taken with the final pick of the first round).

Did any of them crack your top 10, and who else did?

Schmitz: The rest of the names in my top 10 are fairly similar aside from Thybulle and Davis -- I like them both but opted for higher-upside players instead.

I went back and forth on what to do with Clarke, whom I ultimately slotted seventh. On one hand, he's 23, has some limitations in the length and strength departments and hasn't quite been as impactful defensively as I'd hoped. You could argue he doesn't hold the same long-term potential as Herro and Reddish, whom I have slotted behind him. But regardless of age, he gets better every season, is a big reason for Memphis' resurgence and has some Shawn Marion-like qualities that I couldn't ignore. There's something to be said for his constant productivity and winning impact, as he ranks in the top 50 in ESPN's real plus-minus.

I still gave the slight edge to White over Clarke, however. The energetic UNC guard looked borderline unplayable at points this season, but he's on an absolute tear, averaging 22.1 points, 4.5 assists and just 2.1 turnovers on 50.5% shooting from 2 and 40.7% from 3 over his past 10 games. I'd sometimes say White "plays for both teams" given his shot selection, but he has proved me wrong with his rapidly improving floor game and efficiency. If he keeps this up, White, who has long been praised for his work ethic and intangibles, would undoubtedly belong in the top four of this list by season's end.

I rounded out my top 10 with Herro, Reddish and Doumbouya. Although Herro has been hampered by injury and has battled some inefficiency this season, I love his mentality, versatile shooting stroke and potential to develop into more of an on-ball threat à la Devin Booker.

After a rough start to the season, Reddish has been tremendous, looking like Atlanta's top rookie. He's defending, making 3s at better than a 50% clip over his past five games and playing the most efficient basketball of his career. Much maligned for the uneven season he had at Duke, Reddish will ultimately look like a draft-day steal for the Hawks if he can continue to improve his feel for the game. Wings with his size, fluidity and shooting aren't easy to find.

My last spot was between Doumbouya, Porter and Thybulle. Porter has been excellent for Cleveland and would hold as much offensive potential on this list as anyone not named Zion or Morant should it all come together for him. I also love Thybulle's defensive impact. But Doumbouya's combination of age, size, mobility, defensive versatility and shooting potential at the combo forward spot is too intriguing to pass up. If he can remain consistent in his approach and stay locked in on every play, Doumbouya has a chance to be more than just a role player down the road.