Even with most 2019 NBA lottery picks sitting out, enough rookies and returning players have made significant impressions during summer league.

A number of them could earn roster or rotation spots with their standout play before training camp.

Between the three leagues—Salt Lake City, California and Las Vegas—we ranked the top 25 performers heading into July 11, taking into account production, efficiency, impact and the eye test.

Only players who've suited up in at least two games were considered.

Nos. 25-21

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25. Amile Jefferson, Orlando Magic C

Jefferson has been physical and effective from foul line to baseline while finishing and rebounding through contact. In four games, he's averaging 15.8 points and 9.0 rebounds on 56.3 percent shooting, giving Orlando toughness and a high-percentage scorer in the paint.

24. Quinndary Weatherspoon, San Antonio Spurs SG

Signed to a two-way deal, Weatherspoon has averaged 16.0 points through four games between Salt Lake City and Las Vegas play, showcasing smooth, timely slashing and three-level scoring. Enough flashes of shooting and defense should have Spurs coaches feeling optimistic heading into the preseason.

23. Jacob Evans, Golden State Warriors SG/SF

After shooting just 32.4 percent last summer league, Evans looks far more comfortable this July, averaging 14.3 points, 5.0 rebounds and 4.0 assists on 45.7 percent shooting. He's appeared more threatening as an on-ball creator and scorer while maintaining his identity as a jack-of-all-trades, versatile wing.

22. Chris Clemons, Houston Rockets PG

The NCAA's leading scorer in 2018-19, Clemons hasn't been held back by 5'9" size in summer league, totaling 64 points and 17 three-pointers through three games. With a similar green light to the one he was given at Campbell, he has found a scoring rhythm, particularly as a shot-maker off the dribble and catch.

21. Jarred Vanderbilt, Denver Nuggets PF

After playing just 14 games at Kentucky and 17 games for the Nuggets as a rookie, Vanderbilt entered summer league as a scouting priority. He's capitalized on the interest and attention, averaging 12.0 points, 12.0 rebounds, 2.0 assists and 2.0 steals on 53.6 percent shooting. Vanderbilt is reminding viewers not only about his nose for the ball around the basket, but also his versatility as a 6'9" forward who can handle, face up and pass.

Nos. 20-16

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20. Naz Mitrou-Long, Cleveland Cavaliers PG/SG

Already with seven logged games between Las Vegas and Salt Lake City, Mitrou-Long has averaged 16.0 points, 4.9 assists and 4.6 rebounds on 41.9 percent shooting from three. Equipped with streak-shooting ability and playmaking skills, the 6'4" combo guard has given the Cavaliers a lively pop of offense.

19. Jarrett Allen, Brooklyn Nets C

Already proven at the NBA level, Allen has just gone through the motions, effectively providing an inside presence as a finisher and rim protector. He's just getting loose for a bigger regular-season role, one that will now feature Kyrie Irving as the point guard tossing lobs.

18. Brandon Clarke, Memphis Grizzlies PF/C

Quite a few players have been more productive than Clarke. His impact has been the story, however, as his athleticism, energy and nose for the ball have translated to a plus-25 against the Phoenix Suns and a plus-23 against the Los Angeles Clippers. Just as he did at Gonzaga, he's making winning plays without needing dribbles or a heavy dose of shots.

17. Mfiondu Kabengele, Los Angeles Clippers PF/C

The momentum Kabengele built in the NCAA tournament has carried over to summer league, where he's averaging 17.7 points, 7.3 rebounds and 2.0 blocks on 6-of-12 shooting from three. He's stepping into jump shots with fluidity while bringing power and athleticism to the paint for finishing and defense.

16. Drew Eubanks, San Antonio Spurs C

Eubanks has been energetic and efficient, averaging 15.6 points on 71.8 percent shooting through five games. Though limited at both ends, his light feet and mobility have been eye-catching, as he's regularly positioning himself for dunks or layups by moving without the ball and quickly releasing from his screens.

Nos. 15-11

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15. Daniel Gafford, Chicago Bulls C

Gafford has hit the 20-point mark in two of his four games while shooting 63.6 percent throughout summer league. He tallied six blocks in 23 minutes against the New Orleans Pelicans. His skill set is limited, but he's been a force around the basket, using his competitiveness, physical tools and athleticism for finishing, cleanup work and rim protection.

14. Jock Landale, Milwaukee Bucks PF/C

The Australian big man spent last year overseas before arriving in Las Vegas to average 18.3 points and 7.0 rebounds on 8-of-18 shooting from three. He's given Milwaukee a floor spacer and shot-maker, as well as an energizer around the basket who makes plays off rolls and missed shots under the boards.

13. Terance Mann, Los Angeles Clippers SG/SF

A classic glue guy we highlighted as one of the draft's best-kept secrets, Mann has averaged 8.7 points, 11.3 rebounds and 5.7 assists on 60.0 percent from the field. Without needing to look for his shot, he's impacting games by making the right reads as a driver, cutter, passer and defender.

12. Jaxson Hayes, New Orleans Pelicans C

Hayes didn't score 20 points all year at Texas before debuting in summer league with 28 points. His remarkable vertical bounce and coordination have translated to easy baskets above the rim, while a surprising three-point make against the Cleveland Cavaliers should have coaches drooling over the 19-year-old's potential.

11. Carsen Edwards, Boston Celtics SG

Edwards has picked up where he left off in the NCAA tournament, unloading on defenses with his relentless perimeter scoring and shot-making. Averaging 19.0 points on 12-of-25 shooting from three, he's building a case for minutes in Boston's rotation, in which he'd likely work as its second-unit scoring specialist.

10. Tony Bradley, Utah Jazz C

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Stats through four games: 19.0 points, 13.0 rebounds, 1.5 blocks, 56.6 field-goal percentage

Tony Bradley hasn't shown anything new to generate more intrigue from the Utah Jazz or other teams. He's still been one of the most effective summer-leaguers, mostly by sticking to his strengths as a finisher, cutter, low-post player and rebounder.

With zero flash, Bradley has consistently earned himself baskets in the paint by using his body and timing. He takes up space inside to gain position and create easy scoring chances.

Despite entering his third professional season since leaving North Carolina, he's only 21 years old and capable of providing a presence under the rim. To emerge as an NBA rotation player, however, Bradley will either want to become a more threatening mid-range shooter or a steadier rim protector.

9. Mitchell Robinson, New York Knicks C

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Stats through four games: 12.8 points, 11.0 rebounds, 3.5 blocks, 84.0 field-goal percentage

Averaging 11.0 rebounds and 3.5 blocks on 84.0 percent shooting, Mitchell Robinson has been unsurprisingly dominant around the basket in summer league.

He's played to his strengths as a finisher and lob target while flashing special verticality and coordination.

Robinson ultimately looks to be on a path toward eventually leading the NBA in field-goal percentage and blocks, though he'll have to improve his defensive awareness for the whistle. He's totaled 22 fouls in four games.

8. Chris Boucher, Toronto Raptors C

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Stats through three games: 22.7 points, 10.7 rebounds, 1.3 blocks, 44.4 field-goal percentage, 27.3 three-point percentage

The G League MVP and Defensive Player of the Year has been similarly effective in summer league. Chris Boucher has turned heads this July, mostly with an offensive skill level higher than you'd expect from a 6'10" big.

He made a pair of three-pointers in each of his first three games, showing the perimeter range and touch NBA coaches typically want from at least one of their centers.

Boucher's effort level has also been high when running the floor in transition, operating under the boards and playing defense. He continues to build an NBA case around his ability to pick up easy baskets at the rim, stretch the floor and block shots.

7. Tyler Herro, Miami Heat SG

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Stats through six games: 19.5 points, 4.3 rebounds, 3.8 assists, 39.6 field-goal percentage, 33.3 three-point percentage

While most of the top 2019 first-rounders are sitting out summer league, Tyler Herro has been one of the class' top performers.

He's averaging 19.5 points through six games, capitalizing on a green light to work off the dribble (more than he did at Kentucky) or rise for jumpers whenever the urge hits. His extreme confidence has been evident; Herro has shown zero hesitation and a gunner's mentality hunting for shots in transition and the half court.

Herro's shooting form and balance continue to look picturesque. Along with the 2.8 threes he's making per game, he's also dishing out 3.8 assists. That's a reflection on his general skill level, not just as a scorer, but also as a ball-handler and passer.

Quick and competitive defensively, Herro is showing the Miami Heat—and their potential trade partner, the Oklahoma City Thunder—he's both potent and well-rounded.

6. Bruce Brown Jr., Detroit Pistons PG/SG

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Stats through four games: 13.5 points, 8.3 assists, 8.0 rebounds, 1.3 steals, 1.5 blocks, 41.3 field-goal percentage

Placing an obvious emphasis on improving as a facilitator, Bruce Brown Jr. has excelled in a lead-guard role and made good reads to set up teammates.

His facilitating has been a significant summer league development. He's also controlled the pace of games, looking like a pro among NBA hopefuls.

Meanwhile, Brown's athleticism has come to life off drives, missed shots and transition play. He's putting pressure on opposing teams with his attacking, playmaking and defensive quickness. And that will likely be his calling card next season for the Pistons, who should play Brown to spark the second unit.

5. Nickeil Alexander-Walker, New Orleans Pelicans PG/SG

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Stats through two games: 24.5 points, 7.0 assists, 3.5 rebounds, 2.0 steals, 52.8 field-goal percentage, 46.2 three-point percentage

All eyes were locked on Zion Williamson to start the New Orleans Pelicans' summer league experience. As of July 11, the main storyline has instead been the play of Nickeil Alexander-Walker, the team's third first-round pick who's looked more comfortable and commanding than he did down the stretch for Virginia Tech.

While his scoring numbers stand out first, his facilitating has been the more satisfying development from a projection standpoint. He's delivered a number of high-level passes off the dribble, through crowds off ball screens and off penetration. A first-time viewer would believe they were watching a natural point guard, though signs leading up to summer league pointed to Alexander-Walker settling in as more of a secondary playmaker or combo guard.

His 24.5 points per game have been equally impressive, however. He's executed smoothly as a driver, mid-range shot-maker and pull-up shooter.

4. Cameron Payne, Dallas Mavericks PG

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Stats through three games: 20.0 points, 5.0 rebounds, 4.0 assists, 2.7 steals, 51.4 field-goal percentage, 45.8 three-point percentage

At 24 years old and entering his fifth NBA season, Cameron Payne should be expected to rise above the summer league competition. And he has through three games while averaging an efficient 20 points.

Payne looks more comfortable and confident than he has during any regular season. He's getting the shots he wants, and he's also looking for them more often.

Enough off-the-dribble skill and vision have led to four assists per game, but his scoring and shooting are the skills that have truly popped in Las Vegas.

3. Anfernee Simons, Portland Trail Blazers

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Stats through three games: 22.0 points, 4.3 rebounds, 1.7 assists, 55.8 field-goal percentage, 64.7 three-point percentage

A late-season 37-point eruption as a rookie served as a reminder why the Portland Trail Blazers wanted to gamble on Anfernee Simons straight out of high school. Meanwhile, his 2019 summer league has been another positive indicator.

At 20 years old, he's been a dominant scorer through three games, averaging 22.0 points on 55.8 percent shooting. Days after making four of his six threes against the Houston Rockets, Simons put on a shot-making clinic in a loss to the Utah Jazz, finishing 6-of-7 from three for 35 points.

He's knocking down jump shots off the catch, scoring off the dribble and showing nifty footwork maneuvers that create separation. And with ball-handling skills and athleticism, he remains a threat to snake through defenders and get to the hoop.

Simons is ultimately building a case in Las Vegas for regular-season rotation minutes. And given Portland's lack of backcourt depth, he appears on track to play a key role for the Blazers' second unit with Rodney Hood and Zach Collins.

2. Kendrick Nunn, Miami Heat SG

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Stats through six games: 22.0 points, 5.2 assists, 4.3 rebounds, 50.5 field-goal percentage, 38.5 three-point percentage

From California to Las Vegas, Kendrick Nunn is making a case for an NBA roster spot.

It took a year for his game to catch the top prospects in summer league after he finished as college basketball's second-leading scorer behind Trae Young in 2018 and spent the 2018-19 season with the G League's Santa Cruz Warriors.

With mid-range creativity and a three-ball falling at a 38.5 percent clip, Nunn appears to have taken his three-level scoring to a new level. He's also put more of an emphasis on his playmaking, dishing out a combined 13 assists in his last two games.

1. Lonnie Walker IV, San Antonio Spurs SG

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Stats through four games: 24.8 points, 5.8 rebounds, 1.0 assists, 55.1 field-goal percentage, 30.8 three-point percentage

Through four games between Salt Lake City and Las Vegas summer leagues, Lonnie Walker IV has averaged 24.8 points on 55.1 percent shooting, and that's without using much of a three-ball.

He's looked noticeably sharper and more confident inside the arc, both as a shot-creator with pull-ups, step-backs and slashes and as a shot-maker from mid-range zones and at the rim. Walker showed off more range against the Toronto Raptors on Monday, hitting three three-pointers en route to 32 points.

After falling to No. 18 in the 2018 draft and playing sparingly as a rookie, the sophomore 2-guard is reviving optimism in the upside his explosiveness, physical tools and perimeter-scoring skills fueled out of high school.

Stats courtesy of Synergy Sports, Sports-Reference.com