Longtime Dallas Mavericks president of basketball operations and general manager Donnie Nelson is out after 24 seasons with the franchise, the team announced Wednesday.
Nelson's departure comes after internal friction due to the increasing decision-making influence of Mavericks director of quantitative research and development Haralabos Voulgaris, sources told ESPN.
Voulgaris, a former professional gambler hired by the Mavs in 2018, has reported directly to owner Mark Cuban and communicated directly with coach Rick Carlisle despite Nelson's objections, sources said.
The decision for Nelson to leave the franchise was made Sunday, sources said.
Nelson, 58, worked for the Mavericks for 24 seasons, serving as an assistant general manager and assistant coach before being promoted to president of basketball operations. He remained Cuban's top basketball executive for years after the acrimonious departure of his father, Don, the Mavs' head coach and general manager from 1997 to 2005.
"I just want to thank Donnie for his 24 years of service to this organization," Cuban said in the team's statement. "Donnie has been instrumental to our success and helped bring a championship to Dallas. His hard work, creativity and vision made him a pioneer. Donnie will always be a part of the Mavs family and I wish him all the best."
Donnie Nelson has been widely credited for scouting and pushing for the two biggest acquisitions in Mavericks history: the draft-day trades for Dirk Nowitzki and Luka Doncic 20 years apart.
Nelson had strong ties to Europe before joining the Mavs. Those paid off almost immediately with Nowitzki, who was a teenager when Nelson started following him in Germany. Dallas had the sixth pick in 1998 and drafted Robert Traylor for Milwaukee, which had the ninth choice and took the 19-year-old Nowitzki for the Mavericks.
After a rough rookie year and missing the playoffs again his second season, Nowitzki led Dallas to the postseason 12 straight years. The Mavericks lost to Dwyane Wade and Miami in the 2006 NBA Finals before beating LeBron James, Wade and the Heat five years later.
Two decades after targeting Nowitzki, Nelson had Doncic at the top of the Dallas draft board when the rebuilding Mavericks ended up lower than hoped in the lottery with the fifth pick. Figuring that wasn't high enough, the club worked a trade with the Atlanta Hawks, who wanted Trae Young after his sensational freshman season at Oklahoma. Doncic had just helped Real Madrid win the European championship.
Nowitzki and Doncic played together one season before Nowitzki retired. Doncic, 22, has twice been an All-Star and first-team All-NBA selection since then. He is eligible to sign an extension expected to be worth slightly more than $200 million, and strongly suggested he would do so after the Mavs lost to the LA Clippers in the first round of the playoffs for the second consecutive year.
A source said the Mavericks have hired Mike Forde's Sportsology, a consulting firm frequently used by teams hiring general managers, to assist in the search for a new head of basketball operations.
The Associated Press contributed to this report.