The final NBA mock draft board of 2018 has undergone major changes from top to bottom.

For the first time, the projected top three picks aren't all from Duke. Meanwhile, breakout upperclassmen have overtaken multiple freshmen for spots in the 20s.

The emergence of Texas Tech's Jarrett Culver, December's biggest riser, also appears to be giving the 2019 draft field a needed boost. His performance against Duke, even in a loss, was the top storyline in the scouting discussion over the past several weeks.

This draft order is based on the NBA standings heading into Wednesday, Dec. 26.

1. Cleveland Cavaliers: Zion Williamson (Duke, PF/C, Freshman)

It's already become difficult to picture an NBA draft board that doesn't have Zion Williamson at No. 1.

His eye-popping natural talent, production and efficiency coupled with new questions concerning teammates RJ Barrett and Cam Reddish have created a gap between Williamson and No. 2.

His unparalleled athletic ability is translating to a 72.4 two-point percentage, 2.1 steals and 1.9 blocks in only 26.2 minutes per game.

He'd fill a frontcourt hole for the Cleveland Cavaliers, Atlanta Hawks and Phoenix Suns, and he'd fit alongside Kristaps Porzingis in New York. The Chicago Bulls already have a pair of cornerstone bigs in Lauri Markkanen and Wendell Carter Jr., but the franchise isn't in position to pass on the best talent available in favor of filling a positional need. 

Williamson is closing in as a lock to go No. 1, regardless of which team is making the selection.

2. Phoenix Suns: RJ Barrett (Duke, SG/SF, Freshman)

RJ Barrett didn't win any new fans after his 7-of-22, six-turnover performance against Texas Tech on Thursday night.

He'd be on thinner ice if another elite prospect was knocking at the door. But for now, Barrett should still have the benefit of the doubt with lottery teams desperate to add a scorer. 

Averaging 23.8 points and 1.8 threes per game, Barrett puts constant pressure on defenses with his transition attack, driving and confident shot-making. He'd give the Phoenix Suns another high-level offensive weapon between Devin Booker and Deandre Ayton. Although, it may make sense for Phoenix to explore trading down to grab a point guard. 

3. New York Knicks: Ja Morant (Murray State, PG, Sophomore)

Without a clear-cut best player available once Williamson and Barrett are off the board, team needs may come into play at No. 3. And the New York Knicks could have a serious hole at point guard. 

Averaging 23.0 points, 9.3 assists and 7.0 rebounds, Ja Morant has played his way into this tier of the draft.

He strengthened his case even further over the weekend against then-No. 7 Auburn by finishing with 25 points, eight rebounds and seven assists in the 93-88 loss. It was a validating performance that helped Morant look legitimate against a quality power-conference opponent. 

Whether he can improve his jump shot (13-of-45 from three) will be a hot topic among NBA scouting departments.

Regardless, Morant, an A-plus athlete for the position, would give the Knicks an explosive ball-handler who'll put pressure on defenses and set up teammates.

4. Chicago Bulls: Cam Reddish (Duke, SG/SF, Freshman)

Cam Reddish could be slipping. 

He's struggling to create or identify quality scoring chances, and he's suddenly cold from behind the arc. Over his last four games, he averaged only 8.0 points on 23.8 percent shooting.

Questions continue to pop up regarding Reddish's shot creation, explosion around the basket and assertiveness, particularly after his 1-of-7 performance against Texas Tech with dozens of scouts in attendance.

However, Reddish has found himself in a tough spot with the offense running through Tre Jones and Barrett and Williamson being the go-to scorers. He'll earn a pass from certain teams willing to overlook his inefficiency because of his long-term potential fueled by his 6'8" size, an easy shooting stroke and defensive range. 

Without an obvious answer on the board at No. 4, the Chicago Bulls could take the chance that Reddish's issues are more related to an unfamiliar role and fewer opportunities to build rhythm behind Williamson and Barrett. He'd plug a hole for the Bulls at small forward between Zach LaVine and Lauri Markkanen.

5. Atlanta Hawks: Kevin Porter Jr. (USC, SG, Freshman)

Kevin Porter Jr. continues to miss time with a quad injury, but he did enough through five games to crack the tier that follows Williamson and Barrett. 

He won't have to produce like either of them to go this high. The athletic 6'6" freshman will draw interest from lottery teams who'll likely be intrigued by his flashes of explosive finishes, acrobatic buckets and nifty isolation moves.

Porter's size, bounce and advanced scoring skills in terms of shot creation and shot-making hint at long-term potential the Atlanta Hawks should be willing to chase and wait on.

6. Washington Wizards: Bol Bol (Oregon, C, Freshman)

The caution signs may start flickering soon on Bol Bol, who's missing games with an unspecified left foot injury. Given his 7'2" size and skinny legs, teams will have to think about his future durability. 

In the meantime, Bol is averaging 21.0 points on 56.1 percent shooting and has gone 13-of-25 from three. He's knocking down jumpers with comfort, even using dribbles to separate and convert speciality shots out of the post. 

Bol has been a mixed bag defensively, blocking 2.7 shots per game but also getting outmuscled around the basket and showing minimal awareness helping off the ball.

There is substantial risk tied to his body type, style of play and lack of urgency. But Bol's size, length and skill level also give him enormous upside.

7. Orlando Magic: Darius Garland (Vanderbilt, PG, Freshman)

Assuming he's expected to make a full recovery, a torn meniscus won't knock Darius Garland down draft boards. It may even help, as the injury took him out after he averaged 19.8 points through four full games and before any obvious weakness (playmaking efficiency, finishing, defense) could become exposed. 

He was already trending upward entering college, thanks to his standout performance at the 2018 Nike Hoop Summit. 

A quick and shifty scorer who's advanced around the perimeter with his pull-up game and three-point shooting, Garland should intrigue lottery teams that are either looking for a new lead guard or additional backcourt firepower.

8. New Orleans Pelicans: Jarrett Culver (Texas Tech, SG, Sophomore)

Jarrett Culver moved the needle Thursday night when he scored 25 points against Duke in front of dozens of NBA evaluators. It validated the breakout season he was already having.

A more complete offensive player from a year ago, Culver showcased his entire repertoire at Madison Square Garden, including hard drives, counter footwork off the dribble, finishing adjustments at the rim, pull-up jumpers and spot-up three-point shooting. He compensates for his limited explosiveness by taking long strides, timing his moves and demonstrating improved perimeter shot-making. 

Culver has also been a disciplined, tough defender since arriving at Texas Tech.

The 19-year-old shooting guard appears to be on the verge of passing underperforming freshmen on draft boards. 

9. Minnesota Timberwolves: Keldon Johnson (Kentucky, SG/SF, Freshman)

A consistent source of offense for Kentucky, Keldon Johnson continues to impress with outside shooting.

He buried four threes in a win over North Carolina on Saturday after sinking six of seven last week against Utah. That's been a noteworthy development, considering the preseason scouting report listed his jumper as a question mark.

Johnson's signature strength still revolves around his athleticism and attacking. But his improved set shooting helps to reduce perceived risk that was originally expected to follow him into the draft.

10. Brooklyn Nets: Rui Hachimura (Gonzaga, PF, Junior)

Rui Hachimura's gradual year-to-year improvement has been assuring, even if there are still holes in his game.

At 6'8" and 230 pounds, he's emerged as a go-to scorer for Gonzaga. He's able to generate offense using his face-up quickness, coordination around the basket and mid-range touch.

His three-point shooting and defense remain question marks, but a late-lottery team is still bound to fall for his physical tools, continuous development and production for a Top 10 team.

11. Atlanta Hawks (via Mavs): Nickeil Alexander-Walker (Virginia Tech, SG, Soph)

Nickeil Alexander-Walker should be charging up boards, having returned to Virginia Tech as a more dynamic, well-rounded scorer and playmaker. 

At 6'5" with broad shoulders, Alexander-Walker has always had strong positional tools that stood out. This season, though, he's become far more threatening off the dribble while continuing to knock down threes at a convincing 46.8 percent clip.

He'll work as a 2-guard in the NBA, but he's also developed into a sharp pick-and-roll ball-handler who's able to create from the point.

Alexander-Walker isn't explosive, which is the main knock that raises questions over his upside. But between his size, footwork, shooting, budding skill set and production, it's become easier to overlook the breakout sophomore's athletic limitations.

He suddenly has a compelling draft case, even for teams in the late lottery.

12. Utah Jazz: Romeo Langford (Indiana, SG, Freshman)

Romeo Langford has been a constant for Indiana, scoring consistently and efficiently while flashing next-level finishes and dribble jumpers.

He does lack explosiveness and shooting range (10-of-47 from deep), which could prevent him from blowing up in the NBA.

Langford remains attractive for his ability to create and convert shots off the bounce, whether it's with a hard drive, a runner or a step-back. He's shooting an efficient 62.3 percent inside the arc.

Raising his three-point percentage over the next two months would help strengthen his case for teams picking in the top 10.

13. Boston Celtics: Nassir Little (North Carolina, SF/PF, Freshman)

Long-term potential will keep interest in Nassir Little alive, even if he continues to struggle at North Carolina.

At 6'6" and 220 pounds, he possesses an appealing mix of power and quickness, along with a skill set that includes face-up moves and dribble jumpers. 

His tools and athleticism are further ahead of his offense. Having shot 5-of-22 from three with only eight assists all season, Little isn't an advanced shot-creator or shot-maker. But the Atlanta Hawks could be enticed by his standout NBA body, defensive upside and flashes of scoring ability.

14. San Antonio Spurs: Sekou Doumbouya (France, SF/PF, 2000)

Sekou Doumbouya will have to win teams over with his flashes of potential, as he's playing only 15.0 minutes per game.

The 6'9" combo forward has given scouts glimpses of two-way versatility with his ability to face and attack, finish above the rim, make open shots and guard multiple positions. His 12 points on Wednesday and Friday were a season high. 

Doumbouya is missing a bankable skill, but he just turned 18 on Sunday. He'll likely be the youngest prospect in the draft, and he has standout NBA tools, developing inside-out offense and significant room for improvement.

Nos. 15-20

15. Detroit Pistons: De'Andre Hunter (Virginia, SF/PF, Sophomore)

Hunter hasn't made any obvious upgrades to his game since last year. He's still a promising defensive prospect with his 6'7", 225-pound size, length and quickness. He's also 11-of-25 from behind the arc thus far. Hunter's tools and three-and-D create the perception of a high floor, but questions remain about his upside and development as a shot-creator and scorer. 

16. Charlotte Hornets: Jaxson Hayes (Texas, C, Freshman)

Averaging 20.3 points per 40 minutes on 74.6 percent shooting, Hayes' tools, rim running, hands and coordination have stood out under the NBA's scope. He's emerged as a easy-basket big and rim protector who's blocking a spectacular 13.2 percent of opponents' two-point shots. 

17. Miami Heat: Tre Jones (Duke, PG, Freshman)

Jones had to have moved up boards following his 13-point, five-rebound, five-assist, six-steal game against Texas Tech. He impacted the result by applying relentless ball pressure and forcing turnovers, a strength he could build an NBA identity around. His scoring and shooting are clearly behind, but some teams are bound to view Jones as an immediate backup who'll make good decisions and defend with intensity.

18. Houston Rockets: Jontay Porter (Missouri, C, Sophomore)

Out with a torn ACL, Porter won't play another game for Missouri, but he'll still draw plenty of first-round interest. Scouts likely saw enough convincing flashes of three-point shooting, passing and shot-blocking in 2017-18, and he's still only 19 years old. 

19. Boston Celtics (via Kings): Brandon Clarke (Gonzaga, PF/C, Junior)

Off the radar entering the season, Clarke has emerged as a legitimate first-round prospect, turning heads with his athleticism, motor, defensive playmaking (3.2 blocks, 1.5 steals) and flashes of offense. Seeing as Gonzaga's energizer is already 22 and lacks scoring skills, he won't be viewed as a high-upside prospect. Instead, teams will value his floor and the odds of his tools, bounce and nose for the ball translating to easy baskets, defense and hustle plays.

20. Portland Trail Blazers: Coby White (North Carolina, PG/SG, Freshman)

Scouts should overlook White's lack of explosion for his 6'5" size, quickness and skill level as a passer and shot-maker. He's averaging 24.6 points, 6.3 assists and 3.7 threes per 40 minutes, making a first-round case with scoring and playmaking that a number of teams could use for their second units.  

Nos. 21-30

21. Boston Celtics (via Clippers): Grant Williams (Tennessee, PF, Junior)

Williams never popped as a prospect without positional height or athleticism. But he's turned into a potential outlier given how strong the rest of his game has become. Averaging 19.6 points, 8.5 rebounds and 4.2 assists, now seven of 17 from three, the 6'7", 236-pound forward is remarkably well-rounded in terms of skill, feel for the game and defensive IQ. One team is bound to look past his obvious limitations.

22. Los Angeles Lakers: Ignas Brazdeikis (Michigan, SF, Freshman)

Brazdeikis should draw crowds of scouts during conference play after leading undefeated Michigan in scoring heading into 2019. He's a year older than most freshmen, also lacking plus athleticism. But Brazdeikis has become relevant in the draft discussion, impressing with ball-handling moves, crafty finishes, shot-making and a competitive edge.

23. Boston Celtics: Daniel Gafford (Arkansas, C, Sophomore) 

Gafford has asserted himself as a sophomore, leading Arkansas in scoring (17.6 points) by beating defenses with tough finishes and one-handers in the paint. He hasn't made any progress as a shooter, and the inability to defend the perimeter limits him in today's NBA. But this late, a team should see value in Gafford's floor as a rim runner and shot-blocker to bring off the bench.

24. Philadelphia 76ers: Talen Horton-Tucker (Iowa State, SF, Freshman)

Horton-Tucker has drawn attention for his freshman production, but also his unique skill and quickness at 6'4", 238 pounds. He's crafty off the dribble, able to create and make tough shots, including 1.5 threes per game. And he's been an active defensive playmaker (1.7 steals), showing fast hands, feet and instincts. Horton-Tucker isn't built like most guards, and his lack of explosion has been exposed inside the arc. He'll have wiggle room with scouts, however, being that he just turned 18 years old in November. 

25. Oklahoma City Thunder: Naz Reid (LSU, PF, Freshman)

For a 6'10", 240-pounder, Reid has showcased unique scoring ability fueled by ball-handling and speciality shot-making skill with his jumper. It points to mismatch offensive upside. His defense, rebounding and shooting credibility have raised questions about his value, however. Despite Reid's physical tools, he's averaging just 5.3 boards and 0.6 blocks while converting 30.3 percent of his threes and 69.4 percent of his free throws.

26. Indiana Pacers: Ty Jerome (Virginia, SG, Junior)

Despite lacking speed and athleticism—physical strengths that typically hint at NBA upside—Jerome has made a draft case with his shot-making, high-IQ passing and defensive toughness. His ceiling doesn't exceed role player, but the likelihood of him becoming one should interest playoff teams searching for immediate depth. 

27. Golden State Warriors: KZ Okpala (Stanford, SF/PF, Sophomore)

Okpala popped last year for his positional 6'9" size and face-up scoring moves, but he's strengthened his case as a sophomore, appearing sharper off the dribble and more accurate from behind the arc. He's still closer to the raw side, creating the perception he's a project, but also a higher-upside prospect.

28. Brooklyn Nets (via Nuggets) Admiral Schofield (Tennessee, SF, Junior)

Schofield has taken a significant leap forward, now averaging 18.4 points on  41.7 percent from three. He'll draw looks for his massive 6'6", 241-pound frame, shot-making versatility and defensive potential.

29. Milwaukee Bucks: Shamorie Ponds (St. John's, PG, Junior)

Ponds has led St. John's to a 12-0 record while raising his scoring efficiency, three-point accuracy and assist rate and reducing his turnovers per game. Even if teams are still unconvinced about his lead-guard potential, he remains enticing for his ability to catch fire and take over stretches with steak shot-making.

30. San Antonio Spurs (via Raptors): Goga Bitadze (Georgia, 1999, C)

Coming off three consecutive games of at least 23 points, 19-year-old Bitadze is now second in the Adriatic League in scoring. At 6'11", 246 pounds, he has nimble feet and soft hands, and he's extended his shooting range this year, making 10 of his first 24 threes. 

Stats courtesy of Basketball-Reference.com