Key figures within the Dallas Mavericks organization, including current and former staff and individuals close to Dirk Nowitzki, traveled with the team for Nowitzki`s induction into the Naismith Memorial Basketball Hall of Fame in Springfield, Massachusetts, in August 2023. This trip, celebrating the most iconic player in franchise history, served as a brief moment of positivity following a difficult, losing season.
General Manager Nico Harrison was on the trip, having known Nowitzki for over two decades since his Nike days. Casey Smith, the Mavs` Director of Health and Performance, also traveled; Nowitzki frequently credited Smith, who joined in 2004 and was promoted in 2019, with helping extend his career. Nowitzki considered Smith a close friend and trusted him implicitly. Attendees at the Hall of Fame events and private parties organized by Nowitzki`s long-time special projects manager, Lara Beth Seager, recalled nothing unusual during that weekend, which both Harrison and Smith attended with their wives.
However, events that followed this seemingly harmonious weekend initiated a chain of critical behind-the-scenes decisions with profound consequences for the Mavericks during a subsequent disappointing, injury-plagued season. Interviews with over a dozen team and league insiders reveal that while the Luka Doncic era officially concluded on February 2, its true decline, alongside the team`s internal culture, began 18 months prior – the summer *before* the generational talent led the Mavs to the NBA Finals.
Days after returning to Dallas, as the organization still basked in the glow of honoring Nowitzki, Harrison informed Smith he needed a meeting. Smith, who was in Ohio caring for his gravely ill mother, was unable to meet in person, so Harrison arranged a video conference. During this call, Smith was informed his services were no longer required, ending his nearly two-decade tenure. Sources briefed on the discussion stated the vague reason centered on Smith being “too negative,” interpreting this to mean he wasn`t sufficiently agreeable.
“He was 100 percent threatened by him,” a team source told ESPN, suggesting Harrison felt Smith`s influence within the franchise was too significant. “He`s going to show that I`m in charge and nobody else can question that.”
This marked a stunning initial step in Harrison`s restructuring of the health and performance department over two offseasons. Smith`s abrupt departure was followed in June by the dismissals of athletic performance director Jeremy Holsopple and manual therapist Casey Spangler, just days after the team`s NBA Finals appearance.
“You bringing up Casey [Smith] is like almost, it`s kind of a joke,” Harrison said during a recent availability with Dallas reporters. “Like last year, Casey wasn`t around, and we made it to the Finals. No one brought up Casey last year. So, to bring him up this year doesn`t really make sense. He`s been away for two years. So it`s — I`m not even going to comment on that.”
Sources indicated the tense dynamic between Doncic`s representatives – led by agent Bill Duffy and Seager, who became his business manager after Nowitzki introduced them – and Harrison and his new staff was a factor in the GM`s unexpected decision to trade Doncic to the Los Angeles Lakers for Anthony Davis in February. Smith, Holsopple, and Spangler were long-time employees who had helped Doncic, who moved to Dallas as a teenager from Slovenia and Spain, adapt to American culture. They became trusted confidantes for the superstar. However, sources said Harrison viewed them as “enablers,” despite their high respect across the league. Holsopple was the NBA`s Strength and Conditioning Coach of the Year in 2021, and Smith`s role as Team USA`s head athletic trainer included their 2008 and 2012 Olympic gold medal victories.
“We feel that the guys that replaced them have done an amazing job,” Harrison stated. “And again, you`re coming at me from a negative standpoint, and I look at it from a positive standpoint. The guys that we brought in are better.”
According to sources, friction between Harrison`s new hires – director of player health and performance Johann Bilsborough and athletic performance director Keith Belton – contributed to the Mavericks` significant medical issues throughout the season. The team did not employ a full-time manual therapist. At one point late in the season, injuries were so severe that the Mavs struggled to field the minimum eight active players, dropping below .500 before finishing 39-43 to secure the Western Conference`s last play-in spot.
Harrison`s decision to fire Smith, particularly the manner of his dismissal, also alienated Nowitzki from the franchise he proudly served his entire career. Sources said Nowitzki, who now describes himself primarily as a “Mavs fan,” opted against further involvement in basketball operations after Smith`s forced exit. He had previously served as a senior adviser to Mark Cuban, attending practices and offering input when in Dallas.
Sources also stated that Smith`s removal contributed to the departure of Mavs Vice President of Basketball Communications Scott Tomlin, another employee of two decades who was close to Smith, Nowitzki, and Doncic. Tomlin subsequently took on an executive role with the DN Companies and The Dirk Nowitzki Foundation.
“My obligation is to the Dallas Mavericks,” Harrison said. “It`s what`s in the best interest of the Dallas Mavericks, and that`s the most important thing. Again, some of those decisions are going to be unpopular, maybe to Dirk and maybe to the fans, but my obligation is to the Dallas Mavericks.”
Nowitzki and Tomlin have attended only two NBA games since February: Doncic`s Lakers debut in Los Angeles and his return to Dallas on April 9.
“Over the past year, you could already see the team heading in a different direction,” Nowitzki commented in German during a recent podcast appearance for his foundation, declining an interview request. “Now we`re seeing the result of that.”
Derek Lively II, a promising 21-year-old center, was listed as questionable on January 20 due to a right ankle sprain, having missed the previous two games. Under Belton`s oversight, Lively underwent an intense workout before being held out again that night. The plan was for him to play at home two nights later against Minnesota.
However, Bilsborough had concerns and sent Lively for a CT scan. It revealed a stress fracture in his right ankle, sidelining the center for the next 2½ months.
“Somebody should be fired for that,” a team source commented at the time.
Multiple team sources viewed this incident as a symptom of a larger issue. Harrison, however, defended the handling of Lively`s injury, calling his medical staff “elite” and claiming they avoided a potentially catastrophic injury by identifying the stress fracture despite initial clearance. Sources noted Lively`s camp was satisfied with Bilsborough`s communication during recovery.
According to more than 10 team sources, the situation culminated in a loud, heated confrontation between Bilsborough and Belton, escalating from the practice facility`s trainer`s room to the weight room. Harrison did not respond to a question about this incident or others regarding the health and performance group. The Mavericks declined to make Bilsborough or Belton available for comment.
“Not punches, but they were going at it,” one source who saw surveillance footage of the incident told ESPN. “That was coming for a long time,” another team source added.
The tension had been building for months. Harrison reportedly created an awkward dynamic by hiring Belton before Bilsborough, despite Bilsborough being the department head. Sources said Bilsborough did not respect Belton`s expertise.
“He`s a glorified cheerleader,” one team source stated. “But Nico clearly wanted cheerleader energy.”
According to the National Strength Coaches Association database, Belton lacks the required NSCA certifications for NBA strength coaches under the collective bargaining agreement, which also mandates three years of experience post-certification. An NBA spokesperson acknowledged Belton`s lack of required certifications but stated the league accepted his College Strength and Conditioning Coaches Association certifications temporarily, expecting him to obtain NSCA certifications post-season. Belton`s background primarily involved college and professional football.
Some critics described Belton as more of a personal trainer than a modern NBA “body engineer.”
“Johann is a little bit handcuffed in his department,” a team source explained. “[Belton is in] a pivotal role that trains players, but keeps the department in line to a philosophy and everyone working in the same way — [Belton is] none of those things. And then on top of it, the two of them have been beefing since day one, which led to the big blowup.”
“He has shown no respect to Johann the entire year. No collaboration whatsoever. He either ranges from completely standoffish to doing the dumbest s— with a player just to prove a point to Johann. It`s terrible. And you can`t do it that way. You can`t do what he`s done and not put a player more at risk by doing that.”
Bilsborough, an Australian sports scientist with a doctorate, also came from football, having directed performance and rehabilitation for the New England Patriots for five seasons. He did have prior NBA experience as the Boston Celtics` director of sports science from 2017 to 2020. A Celtics source described Bilsborough as highly intelligent but more academic than practical, tending to be “divisive when he disagrees with somebody.” Bilsborough and Art Horne, the Celtics` head athletic trainer and performance director at the time, often disagreed, creating a “cold war” between factions within the department. Bilsborough left after three seasons; Horne remains, having been promoted.
Bilsborough reportedly struggled to build rapport with Doncic and his personal “body team.” With Harrison having already alienated Doncic by moving on from trusted staff, Bilsborough, replacing the respected Smith, never earned Doncic`s full trust or respect, sources said.
It`s notable that the New York Knicks, led by former Mav Jalen Brunson, hired Smith as their vice president of sports medicine as soon as his Mavs contract expired. The Knicks also hired former Mavs athletic trainer Heather Mau. The Knicks have seen a significant reduction in games lost to injury this season, and Smith and Mau oversaw Brunson`s recovery from a severe ankle sprain.
Brunson discussed how much he would miss “the Caseys” (Smith and Spangler) and Mau after leaving the Mavs in 2022. JJ Redick, who briefly played for Dallas, mentioned still being in a group chat with those staff members. “Not a lot of people understand how much of a difference those people make in your everyday life,” Brunson said. “They`re really special. And the fact that they`re so personable and you can talk to them about anything, that makes it even harder [to leave]. It`s not just work. They know how to be people.”
Mavericks sources, agents, and associates of current players are divided on Bilsborough. Some view him as competent and evidence-based, while others are critical, citing his perceived lack of relationship-building with players and staff, infrequent travel early in the season, and sometimes overly optimistic injury return timelines. “If you`re not around the team all the time, you shouldn`t be involved in decision-making,” a team source commented. Another, while praising Bilsborough, added, “That is definitely a challenge. You can`t be perceived as this guy that hovers around. You got to be able to get in and obviously that`s Casey`s magic.”
Harrison defended the health and performance group, asserting most injuries were unavoidable contact injuries. However, players frequently re-aggravated injuries or sustained related issues upon returning. “It`s hard to say what a guy should have for a contact injury, but how fast they come back or how likely they are to reinjure it, that`s another story,” a team source said, attributing return-to-play issues to the medical and performance staff. Another source highlighted dysfunction beyond the medical department, suggesting pressure to keep players on the floor was influenced by the front office`s desire to validate past trade decisions. “I think there`s a dysfunction on an organization level because of the trade itself,” this source added.
A notable example is Anthony Davis`s left adductor strain during his Dallas debut on February 8, occurring upon his return from an abdominal strain sustained days before the trade. Motivated to make a good impression on outraged Mavs fans, Davis admitted he returned too soon but stated it was his decision in consultation with his personal medical team and Bilsborough. “They meet and communicate every day,” said Davis, who works with his own staff instead of Belton, claiming “Everybody is one big team.”
However, multiple sources dispute this unified portrayal regarding Bilsborough and Belton, stating their discord harmed the team. “With all the great organizations, the performance and medical [staffs] are seamless,” a team source noted. “And here they`re just completely separate and at odds. It`s pretty clear to see the effect of the divide. The division created an unfortunate environment that ultimately the players had to suffer from.”
Months before Smith`s exit, Doncic and Seager hired Real Madrid physiotherapist Javier Barrio Calvo and Slovenian national team strength coach Anze Macek, both known to Doncic, to work for him. This followed a trend of NBA stars employing personal medical teams. The hires came after Doncic`s nagging quadriceps injury contributed to the Mavs` poor finish in 2023. Doncic`s camp envisioned seamless collaboration with Smith. With Smith gone, Holsopple became the primary liaison.
Doncic`s camp considered the first season of this arrangement successful. He led the league in points, rebounds, and assists during the regular season and became the first player to lead the league in these categories plus steals in the postseason, also leading in total minutes played. “You don`t perform like that … if you`re a fat, drunk pig,” a friend of Doncic`s remarked, feeling the Mavs portrayed him negatively after the trade, crushing Doncic`s dream of staying in Dallas long-term.
Despite historic production, Harrison was reportedly concerned about Doncic gaining weight while managing a heavy workload. Tension grew between the GM and the increasingly isolated superstar and his camp. Bilsborough entered a difficult situation and struggled to connect with Doncic`s group. Sources said Mark Cuban, who prioritized Doncic`s well-being and worked with Seager for years, offered to mediate. However, Harrison had reportedly sidelined Cuban from basketball operations under the new governor, Patrick Dumont, and wasn`t willing to yield ground.
Matters worsened when Doncic suffered a left calf injury during a scrimmage just before training camp, initially thought to be a bruise. After experiencing significant soreness in the first practice, an MRI revealed a Grade 1 strain, sources said, though the Mavs did not disclose this detail. Doncic missed the preseason and, sources added, gained over a dozen pounds, frustrating Harrison and others in the organization.
Doncic, who also used his own doctors instead of the Mavs` physicians, was diagnosed with a sprained right wrist on November 20. Sources said Harrison and the Mavs` medical staff viewed this diagnosis as a potential cover-up to allow Doncic time to improve his conditioning and lose weight after a slow start by his standards.
On November 29, a day before the fifth game he missed, a television in the media room showed a feed of Doncic scrimmaging, primarily taking long jumpers. A team employee quickly changed the channel, claiming uncertainty about how the feed became available. It was not shown again.
Barrio Calvo and Bilsborough communicated regularly but often disagreed, sources said. Meetings involving Harrison, Bilsborough, Seager, Barrio Calvo, and Duffy were frequently tense and unproductive. Doncic did not work with Belton at all.
Tension escalated significantly after Doncic suffered another left calf strain on Christmas Day, his fourth in 28 months. Doncic`s camp believed he returned too quickly from a heel bruise and was playing on his toes to avoid discomfort. Harrison blamed poor conditioning. The sides also drastically disagreed on the return timetable after the MRI. Bilsborough reportedly estimated two or three weeks, while Doncic`s team insisted on six weeks. They ultimately prevailed, targeting a February 8 return.
“That deepened the divide,” a source stated.
Doncic avoided putting weight on his left leg for two weeks. While an MRI four weeks later was encouraging, the six-week plan remained in place. Another major disagreement arose when Doncic refused Harrison`s request to join the team for a five-game road trip leading up to his planned return date. Harrison reportedly complained that Doncic was holding the team “hostage,” sources said. Doncic`s camp argued he benefited more from around-the-clock access to the practice facility for intensive, multi-hour workouts, which were difficult to replicate on the road. Harrison countered that Doncic needed to scrimmage. Doncic`s camp offered for him to practice with the G League team in Frisco.
The next communication from Harrison to Doncic`s camp was to announce the trade he had been secretly negotiating with the Lakers was finalized.