Per Steve Kyler of Basketball Insiders, Noel rejected a Mavericks contract offer in the range of $17.5 million per year at some point this offseason.
The Philadelphia 76ers traded the former first-round pick to the Mavericks on Feb. 23.
Michael Scotto of Basketball Insiders reported Monday that Noel changed representatives by hiring Rich Paul of Klutch Sports.
Chris Barnewall of CBS Sports said Noel's decision to switch agents in the middle of free agency, especially at this late date, is "unprecedented." Barnewall added that Paul represents stars like LeBron James and Eric Bledsoe but is "also known for very long holdouts."
Dan Feldman of NBC Sports noted in May that the Mavericks can offer Noel a max contract of $146 million over five years, while other teams can offer $109 million over four years.
In 22 games with Dallas, Noel averaged 8.5 points and 6.8 rebounds. As a restricted free agent, he can sign an offer sheet from any NBA team, and the Mavericks would have the option to match.