For the third straight offseason, the Dallas Mavericks have overhauled their health and performance staff. This time, general manager Nico Harrison dismissed long-time head athletic trainer Dionne Calhoun and athletic performance director Keith Belton according to ESPN insider Tim MacMahon. The decision follows a disappointing season in which the Mavericks finished 39-43 and missed the playoffs. Injuries played a key role in their decline, and now Harrison appears to be shifting blame and making sweeping changes. Nico Harrison firing Calhoun and Belton barely scratches the surface of what’s unfolding.
Is Nico Harrison Correcting Course or Covering His Tracks By Firing Belton And Calhoun
Calhoun had been with the team for 21 years and was one of the last remaining staffers from the era of Casey Smith, the former director of health and performance. Harrison dismissed Smith in 2023 despite his respected reputation across the league and a strong bond with players like Dirk Nowitzki and Luka Dončić.
A Pattern of Dismissals
Smith’s firing came under particularly harsh circumstances. After returning from Nowitzki’s Hall of Fame induction, Harrison demanded a meeting. Smith, in Ohio with his dying mother, proposed a video call instead. During that call, Harrison abruptly ended Smith’s nearly 20-year tenure with vague reasoning centered on being “too negative.”
That firing marked the start of a broader purge. Nico Harrison also fired Jeremy Holsopple and Casey Spangler—both trusted by Doncic and vital to his development in Dallas. Harrison believed they had grown too close to the star, even labeling them “enablers.”
However, the people Harrison replaced them with brought new problems. One of them, Belton, lacked the proper certifications required by the NBA’s collective bargaining agreement. He also clashed frequently with new health director Johann Bilsborough. This tension exploded into a heated confrontation during the season, one that multiple team sources confirmed.
The Lively Incident
The dysfunction culminated in the mishandling of rookie center Dereck Lively II’s injury. Lively was expected to return from an ankle sprain, but under Belton’s supervision, he endured a high-intensity workout.
Shortly afterward, a CT scan—prompted by Bilsborough’s concerns—revealed a stress fracture. Lively missed nearly three months. One source summed up the organization’s frustration: “Somebody should be fired for that.”
And now, somebody was. Nico Harrison fired coach Belton—both central to that misstep. While Harrison publicly praised his staff’s attentiveness, many inside the organization see it as damage control.
Harrison claimed the staff avoided catastrophe by acting on Lively’s symptoms. But that glosses over the fact that the player was nearly cleared to play with a serious fracture. Nico Harrison firing personnel points to a broader pattern of reactive leadership rather than proactive care.
Culture vs. Control
Insiders suggest the conflict goes deeper than injuries. Harrison allegedly viewed Smith and his former staff as threats to his authority. A source said, “He was 100 percent threatened by him.”
The GM’s actions indicate an effort to consolidate control over the organization’s culture. This approach may have alienated key figures in Dončić’s circle and contributed to the deteriorating relationship that led to his shocking trade to the Los Angeles Lakers for Anthony Davis.
Even during Dallas’ brief return to contention, cracks remained behind the scenes. Harrison publicly defended his hires, stating, “The guys that we brought in are better.” But just months later, Harrison fires coach Belton—his own hand-picked replacement for Holsopple.
Unanswered Questions
The Mavericks declined to comment on several questions regarding the team’s medical operations. Bilsborough and Belton were not made available. Footage of their argument was reportedly reviewed internally, but there’s no word on disciplinary action beyond Belton’s dismissal.
As injuries mounted and tension grew, the front office scrambled to field even eight active players late in the season. The organization never hired a full-time manual therapist after Spangler’s dismissal. The result? A team riddled with injuries and chemistry issues, limping to a 39-win finish.
Is Harrison Righting the Ship or Rewriting the Narrative?
Harrison has now fired both the award-winning staff and their replacements. He dismissed trainers trusted by legends like Nowitzki and Dončić. Nico Harrison firing Belton doesn’t just describe an action—it encapsulates a leadership style built on replacing dissent with obedience.
Is he correcting course or covering his tracks? That remains unclear. But one thing is certain: the Mavericks’ internal dysfunction has created ripple effects that could haunt the franchise for years to come.
Will Harrison’s latest hires fare any better? Or will they too become casualties of a leadership model that prioritizes control over collaboration?
Time will tell.
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