The Dallas Mavericks have lost one of their most valuable coaching assets as assistant coach Sean Sweeney has agreed to become the associate head coach of the San Antonio Spurs under Mitch Johnson. ESPN's Shams Charania announced the move Sunday afternoon.
This represents a crushing blow for the Mavericks, as Sweeney has been widely regarded as one of the NBA's premier defensive minds. His departure removes a key architect of Dallas's defensive transformation and a coach who was instrumental in the team's recent playoff success.
Sweeney joined Jason Kidd's staff in 2021, reuniting with his longtime coaching partner after previous collaborations in Brooklyn and Milwaukee. The Saint Paul, Minnesota native immediately made his mark in Dallas, helping transform the Mavericks from a 21st-ranked defense in 2020-21 to a top-seven unit in his first season. That defensive improvement was crucial to Dallas's run to the Western Conference Finals in 2022.
Known for his tireless work ethic and sophisticated defensive schemes, Sweeney became one of Kidd's most trusted assistants. His ability to develop young players and adapt defensive strategies to different personnel made him invaluable during crucial playoff moments. Kidd has consistently praised Sweeney's potential, stating during the 2024 NBA Finals that "he'll be a coach one day and it's a great partnership."
The timing of Sweeney's departure is particularly challenging for Dallas, as his contract was set to expire at the end of this month. The Mavericks have already experienced significant coaching staff turnover this offseason, and losing their defensive coordinator creates another major hole to fill.
Sweeney's move comes after he was a finalist for multiple head coaching positions over the past two summers, including with the Detroit Pistons and Phoenix Suns. His reputation as a defensive mastermind and player development specialist made him one of the most sought-after assistant coaches in the league.
According to Marc Stein, Dallas's natural response would be to approach coaching consultant Frank Vogel about moving into Sweeney's role, but Vogel has been comfortable staying in his consulting position while awaiting his next head coaching opportunity.
The loss stings even more considering San Antonio is a division rival. The Spurs landed one of the NBA's top defensive minds to help establish their new era under Johnson, while Dallas must now find a way to preserve the defensive foundation that Sweeney helped build during his four transformative seasons with the organization.