Luka Doncic has been everything the Dallas Mavericks hoped for in his first month in the NBA. The no. 3 overall pick in this year’s draft started his career on a tear, and hasn’t slowed down yet, averaging 19.1 points on 45.3 percent shooting, 6.6 rebounds, and 4.3 assists per game. There aren’t many players, regardless of age, with his combination of size (6-foot-7 and 218 pounds), scoring, and passing ability. Doncic, at 19, already looks like a franchise player. Now the question is how will Dallas build around him.

Doncic has been one of the keys to a hot streak (7-2 over their past nine games) that has pushed the team into playoff contention. The Mavs, now back at .500 after a slow start to the season, are part of a massive clump of teams in the middle of the Western Conference standings. There isn’t much separation either way. Dallas is 3.5 games out of the no. 1 seed and 1.5 games out of no. 14. Their current success may not be sustainable. Doncic (plus-0.8 in 607 minutes) is their only starter with a positive net rating, and the team has some structural issues that could flare up over the course of the season.

Their starting five is a mishmash of players at different stages in their careers. Harrison Barnes, at 26, is the only one in his prime. Their primary ball handlers (Doncic and Dennis Smith Jr.) are still establishing themselves, and they are flanked by veterans (Wesley Matthews and DeAndre Jordan) in the last seasons of their contracts. The five have not clicked this season, with a net rating of minus-8.8 in 150 minutes together, one of the worst figures among all starting lineups. The Mavs bench has been winning games for them.

Dallas has always had a strong second unit under head coach Rick Carlisle, but the team’s past success came from his habit of staggering lineups so that four reserves played with Dirk Nowitzki. This season has been different. Dirk has been out while recovering from ankle surgery, and the Mavs backups have still been blowing teams off the floor. J.J. Barea, Devin Harris, Dwight Powell, and Maxi Kleber all have net ratings higher than plus-10. Carlisle is one of the best coaches in the NBA at plugging players into specialized roles that fit their skill sets.

“We really try to keep our role definition as simple as possible. We have gone through it with all of our players. They all have a laminated sheet that has five things that are expected of them,” Carlisle told me after practice on Monday.

Finding roles hasn’t been as easy with the starters. The Mavs returned three from last season (Smith, the no. 9 overall pick in last year’s draft, Matthews, and Barnes) but all three have had to adjust to playing with a ball-dominant wing in Doncic. Barnes and Matthews hunted for their own shot with impunity the past two seasons, while Smith has never had to share ballhandling duties before. Jordan has been a high-level roll man this season, but he’s a 30-year-old with a lot of miles on his body, and who no longer has the energy to go all out on both ends of the floor. He has not been able to cover on defense for Smith and Doncic, both of whom have been sieves through the first month of the season.

Defense was always going to be an issue for two young players with that much offensive responsibility. Carlisle has been focused more on building chemistry between the two on offense. Smith has been up and down in his second season, averaging 14.1 points per game on 44.3 percent shooting, and 3.9 assists and 3.1 turnovers. He hasn’t figured out how to use his incredible athleticism to affect the game. He’s a streaky shooter who struggles to get to the line (2.9 free throw attempts per game this season) and doesn’t make players around him better. There’s a huge learning curve for young point guards in the NBA, one Smith is trying to master while also learning a new role on offense. His usage rate, number of touches, and average time of possession have all dropped from last season.

“The goal for Dennis is for him to generate pace in the game offensively, and be the tone-setter on the ball as the point guard defensively,” said Carlisle.

Playing with Luka has helped him in some areas. Smith’s 3-point shooting has improved significantly, from 31.3 percent on 4.9 attempts per game to 39.3 percent on 3.8 attempts per game, and there’s a clear line between that improvement and his new role. He shot 37.2 percent on catch-and-shoot 3s and 27.4 percent on pull-up 3s as a rookie, and he’s cut his number of attempts in the latter category almost in half. Smith is so fast that it’s difficult for defenders to stay in front of him on closeouts, and the defensive attention that Doncic attracts has given him more room to finish at the rim. According to the tracking numbers at Synergy Sports, Smith has gone from being in the 26th percentile of players leaguewide at finishing inside in 2017-18 to 58th this season.

“I don’t mind playing off the ball at all,” Smith told Marc J. Spears of The Undefeated before the season. “[Luka] is a good enough player with a high enough IQ that I can play off the ball and still be effective.”

Smith showed promise as a playmaking point guard as a rookie, but he may end up as a scoring guard and secondary playmaker next to Doncic. The two could become a dynamic pick-and-roll combination, a look the Mavs have yet to use this season. Smith could turn the corner and get to the rim if the defense sticks to Doncic when he’s setting the screen, while Doncic could make plays rolling to the basket in four-on-three situations if the defense focuses on Smith. That synergy is mostly theoretical at this point, though, especially on nights when Smith’s jumper isn’t falling.

Doncic might be sacrificing more than Smith when the two play together. That became clear in the Mavs’ 113-104 victory over the Celtics on Saturday, which Smith missed with a wrist injury. His absence allowed Carlisle to go to a lineup he hasn’t used much this season: Luka at point guard with three bigger wings (Matthews, Barnes, and Dorian Finney-Smith) and one center (Jordan) around him. Dallas switched more screens on defense while hunting mismatches with Doncic in the pick-and-roll. Doncic finished with a career-high eight assists, picking apart Boston out of the post.

That was Doncic’s role last season as an 18-year-old for Real Madrid, when he was the MVP of the EuroLeague. A 6-foot-7 player with his ability to handle the ball, shoot off the dribble, and make plays on the move gives his team a lot of lineup flexibility. They can surround him with length and athleticism in bigger lineups, or play him with multiple ball handlers in smaller ones. Carlisle has been using Doncic in the latter to maximize Smith, but the former would make Doncic’s life easier, particularly on defense.

It might not be possible for the Mavs to prioritize Doncic and Smith at the same time. Doncic has a net rating of minus-5.5 in 405 minutes with Smith and plus-10.3 in 202 minutes without him. One solution that a lot of NBA teams use is staggering the minutes of their two lead ball handlers to give each time to run the offense unimpeded. The problem for Dallas is that giving Smith more time with the second unit would mean playing him next to another point guard (Barea) who needs the ball even more than Doncic. Smith and Barea were like oil and water last season, with a net rating of minus-7.7 in 395 minutes together.

The Mavs are caught in a dilemma. There’s no spot in the rotation for Smith if they play Doncic at point guard, but they can’t afford to give up on Smith, either. The long-term consequences are too high. Their cupboard is almost completely empty without him. They have only two other players under 26: Finney-Smith, an undrafted free agent in his third season in the NBA, and Jalen Brunson, the no. 33 overall pick in this year’s draft. Both have shown promise this season, but neither is likely to become a future star. Plus, they may not have a first-round pick next season if they don’t tank. Unless it winds up in the top five, they owe their pick to Atlanta as part of their trade to acquire Doncic on draft night.

Mavs owner Mark Cuban has prioritized flexibility and clearing salary-cap space over the past few seasons, but he has never landed a big fish, which has kept the franchise treading water without either building through the draft or committing to a core in free agency. So while the team has only $52 million in salary on their books for next season, there’s no guarantee they’ll do anything with it. They may end up gambling on restricted free agents again, like they did with Barnes and Chandler Parsons. Neither lived up to his contract in Dallas.

It’s hard to use cap space effectively. Philadelphia has two stars in Joel Embiid and Ben Simmons, and it still couldn’t find any takers last summer. The Sixers pivoted to trading for Jimmy Butler because they had the assets to, including two starters on affordable contracts in Dario Saric and Robert Covington, which the Mavs don’t have. The earliest future first-rounder Carlisle’s team can even offer in trades is in 2021. Dallas needs Smith to either become a high-caliber player, or turn into a piece that brings one back in a trade, but that may take years, even in a best-case scenario.

Undersized point guards need time to figure it out. Kemba Walker spent three seasons in college and didn’t become an efficient offensive player until his fifth season in the NBA. Jeff Teague spent two seasons in college and didn’t become a starter until his third season in the league. Smith spent only one season at NC State. Dallas knew he would be a project when it drafted him. The Mavs just couldn’t have predicted a player like Luka would fall in their laps the next summer.

The Mavs have an impossibly polished rookie and one of the best benches in the NBA, but they need more to become an actual contender. They have only the eighth-best net rating in the West (plus-1.4) despite having the second-easiest strength of schedule in the entire league so far, per the numbers at ESPN. The clearest path to relevance is for Smith to make a leap, which puts more pressure on Doncic. He has to make Smith better even though he’s better without Smith on the floor. Dallas doesn’t just need Doncic to reach his potential. The Mavs need him to help Smith reach his.