Mavericks, Nico Harrison dismiss several members of team’s training staff

After a season full of injury misfortune, an overhaul of the Dallas Mavericks’ health and performance group has officially begun.

Mavericks general manager Nico Harrison is making significant changes to the team’s health and performance group, according to a person with knowledge of the moves. Among them, head athletic trainer Dionne Calhoun and athletic performance director Keith Belton have been relieved of their roles.

This continues the trend of major turnover to the Mavericks’ training staff since the dismissal of former director of player health and performance, Casey Smith, before the 2023-24 season. Calhoun, who has worked on the Mavericks’ staff for 21 years, is one of the final holdovers from Smith’s staff.

Calhoun joined the Mavericks as an assistant athletic trainer in 2004. Ten years later, he was named associate head trainer, and in 2019 he was named head athletic trainer. His lengthy amount of athletic training experience also includes time as an athletic trainer for Team USA in the 2019 FIBA World Championships in Beijing and the 2020 Tokyo Olympics.

Mavericks

USA’s head athletic trainer Dionne Calhoun makes his way to the bench before the gold medal basketball game against France at the postponed 2020 Tokyo Olympics at Saitama Super Arena, on Saturday, August 7, 2021, in Saitama, Japan. Calhoun serves as the associate head athletic trainer for the Dallas Mavericks during the NBA season. (Vernon Bryant/The Dallas Morning News)(Vernon Bryant / Staff Photographer)

Belton, who joined the Mavericks this season from UCLA, where he spent three years as the director of football performance. Prior to UCLA, he served as director of sports performance for OLLIN Athletic Sports Medicine in Texas. Belton also played in the NFL with stints with the Detroit Lions, Chicago Bears and Denver Broncos.

Harrison declined to comment on the moves.

Just four seasons ago, the Mavericks — under Smith’s leadership — were named NBA Trainers Association staff of the year for a second consecutive year. This season, the second since Smith’s contract was not renewed, Dallas lost 354 player-games to injury and illness during the 2024-25 season, the second most in franchise history.

The Mavericks finished 39-43 this season, failed to qualify for the playoffs and were ravished by injuries to several key players, including Kyrie Irving, Anthony Davis, P.J. Washington, Dereck Lively II, Daniel Gafford and formerly Luka Doncic.

In three cases – Davis, Lively and Washington – players returned to games or practice from injury, quickly suffered aggravations or re-injuries, then missed significant time.

According to NBA insider Marc Stein, Lively’s right ankle stress fracture was at the center of significant tension in February between Belton and director of performance and rehabilitation Johann Bilsborough — who joined the team’s medical staff last season.

Lively was initially diagnosed with an ankle sprain January and was slated to return after three games, but was shut down because further evaluation revealed the stress fracture that kept him sidelined until April 2.

“It actually goes to show the strength of our medical team,” Harrison said during his infamous roundtable discussion with reporters, “because he was cleared to play, but his signs and symptoms, our medical team knew it was something more, and so that’s why they went and tested them again and saw the CT scan, which they actually avoided a potential catastrophic injury.”

Harrison defended the team’s medical staff twice during his final two availabilities of the season.

“Ninety percent of our injuries before the [Luka Doncic] trade were contact injuries,” Harrison said in his end-of-season news conference in April. “That means they’re unavoidable. … Now, in terms of our medical staff, they’re elite, and of course, they’re not happy with the amount of injuries, but a lot of those are unavoidable.”

With Calhoun and Belton no longer employed by the Mavericks, the team’s medical staff includes Bilsborough, Jana Austin

Staff writer Brad Townsend contributed to this report.

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