In early February, during the second quarter of a home game against the Golden State Warriors, Luka Doncic carelessly turned over the ball and received feedback from a Dallas Mavericks employee he didn’t care for: Haralabos Voulgaris, a well-known sports gambler hired by team owner Mark Cuban in 2018. Voulgaris, sitting with an open laptop in his typical courtside seat across from the Mavericks’ bench, motioned downward with his hands, which Doncic specifically interpreted as Voulgaris telling him to calm down, multiple team and league sources tell The Athletic. Doncic snapped back, telling Voulgaris, according to one source’s recollection, “Don’t fukking tell me to calm down.” The same sources say Voulgaris later professed that his motion wasn’t solely directed at Doncic, but regardless of intent, it only worsened an already inflamed relationship between the two. Doncic, multiple league sources say, intends to sign the supermax extension — which he will be eligible for once named to this season’s All-NBA team — with Dallas, worth more than $200 million over five seasons after his rookie contract expires next summer. “I think you know the answer,” he said, smiling, when asked whether he would at last week’s exit interview. But a high-level power broker within the league says the Mavericks recognize that there’s urgency to build a contending team around Doncic after losing in the first round in each of the past two seasons. The clock is ticking. Internally, there are concerns the front office’s dysfunction has hurt its ability to do so — and that poor relationships Doncic has with key members of the franchise, including Voulgaris, could impact his current desire to remain in Dallas long-term. The team’s most recent postseason defeat against the LA Clippers served as a direct indictment on the roster constructed around him. Can Mavericks management remedy that in time? Or, as some team sources fear, will they pay the price for the dysfunctional dynamics that exist in some corners of the organization? Dallas announced Voulgaris’ hiring in the fall of 2018 with a title — director of quantitative research and development — that vastly understated his actual role. Multiple league and team sources tell The Athletic that Voulgaris has been the most influential voice within the Mavericks front office since joining the team, either initiating or approving virtually every transaction made over the past two seasons. Those same sources add that Voulgaris has frequently gone as far as scripting the starting lineups and rotations for longtime head coach Rick Carlisle. That influence has spanned Doncic’s three seasons in Dallas. While he had been drafted prior to Voulgaris’ arrival — Donnie Nelson, the team’s longtime president of basketball operations, was the driving force behind trading up to acquire the Slovenian wunderkind, a process he described in detail to The Athletic last year — Cuban had sought out Voulgaris’ basketball advice in the years before putting him on the team’s payroll. As one team source says, “Mark Cuban is the most powerful person in the organization, but whoever he’s listening to is second.” Cuban was won over by Voulgaris’ vision: an analytics-driven spread pick-and-roll offense with Doncic as the focal point which he has tried implementing in the past seasons. It’s unclear when the Cuban and Voulgaris relationship began, but their coming together is perhaps unsurprising given Cuban’s origin as a self-made tech billionaire whose first major purchase was the Mavericks. Voulgaris has never been shy about his desire to run a team. In an ESPN feature from 2013, Voulgaris is quoted as saying, “The whole process (of becoming a highly successful gambler) has led me to believe that I’d be able to put together a better team than almost any general manager in the league. If not maybe all.” The way Voulgaris tells it — the ESPN feature is the only notable reporting ever focused on him, and he declined an interview request from The Athletic shortly after being hired — he began gambling on the NBA in the late 1990s and had made millions by the early 2000s. His success, he says, came in part from an instinctual reading of certain coaches. It finally failed him during the 2003-04 season, causing him to lose much of his gambling wealth and step away temporarily, only returning once he’d developed an analytics model that brought back his old edge. He says he did exactly that, his new model beating the odds at a rate higher than five percent. In 2009, he gave up gambling again to consult for an unnamed NBA franchise. The advisory role lasted one season; he returned to his previous life afterward and began publicly promoting himself. In the coming years, he became a well-known presence in the basketball world. Voulgaris spent a limited amount of time around the Mavericks during his first season of employment, attending about one-quarter of the team’s games. He attended fewer games the following season, but his imprint on the team’s roster grew substantially that offseason. It was Voulgaris who initiated the team’s acquisitions of Seth Curry and Delon Wright, with multiple sources telling The Athletic that Voulgaris believed Wright should start next to Doncic. “He was the only person that believed that,” one team source says. Wright did start the season opener before being moved to a full-time bench role the following game, barely playing in the team’s first-round defeat in the 2020 postseason. He was traded that offseason. Because Voulgaris’ influence was greater than his official role, those within the front office — and executives around the league who interacted with them — were often confused about who actually held power. “We had two general managers,” a team source says. Nelson remained the team’s president of basketball operations, a role he has held since 2005, and other executives and agents continued largely communicating with him or Cuban regarding personnel matters. Nelson continued to spearhead major moves, including trades for Kristaps Porzingis and Tim Hardaway Jr. in 2019, Josh Richardson in 2020 and J.J. Redikk in 2021. But team sources say Voulgaris was supportive of the transactions — or explicitly approved them. Multiple league and team sources point to the 2020 draft as a particularly egregious example of Voulgaris’ power, an evening one source described as “embarrassing.” Most members of the scouting department joined the team’s war room remotely through Zoom and were surprised when Voulgaris, attending in person, didn’t consult them for either of the team’s first two selections (Josh Green and Tyrell Terry) despite disagreements they held with at least one of the players he picked. “What did (he) sell to Mark to make him believe (he) can do this?” asks one source with an intimate knowledge of the situation. “Nobody knows.” It marked another throughline of Voulgaris’ tenure with the Mavericks: that his personality and decision making has steadily irritated and exasperated the team’s front office employees and players with both his decision making and personality over the course of the three seasons he’s been employed. “He doesn’t know how to talk to people,” that same source says. That’s best exemplified by Dallas’ franchise player disliking him. Doncic’s strained relationship with Voulgaris predated their incident in February, multiple sources say. It wasn’t the only incident, either. This season, Voulgaris attended his first game in mid January, frequently appearing courtside at home and also traveling with them on the road in the months that followed. In mid-April, during the final minute of a home defeat to the New York Knicks, Voulgaris was seen on the game’s broadcast footage standing up and leaving with about 45 seconds remaining. While the Mavericks were trailing by 10 points at the time, they cut the deficit to six and extended the game seven more possessions before eventually losing. Doncic noticed Voulgaris’ early departure. In the locker room after the game, multiple league and team sources say he told teammates he viewed Voulgaris leaving before the game’s conclusion as him quitting on them. Voulgaris would not attend another game the rest of the year. Multiple team sources confirm Voulgaris remained involved in the team’s gameplans and in-game adjustments in a remote role. But Voulgaris, who earlier this season appeared likelier than not to wrest further control over the front office and perhaps even drive out Nelson entirely, now heads into a summer with his contract set to expire and uncertainty surrounding his future. When reached for comment on Monday, Cuban defended Voulgaris’ involvement. “I really like what Bob brings to the table. He does a great job of supporting Rick and the front office with unique data insights.” Cuban added: “Bob has a great grasp of AI and the opportunities it create for gaining an advantage. Which is important to me. But he isn’t any more influential than any other data source on the team.” Voulgaris declined to comment for this story when reached on Sunday.