Mason's agent, Roger Montgomery, confirmed to The Associated Press on Wednesday night that talks between the nine-year NBA veteran and the Thunder had broken down and the two sides wouldn't be agreeing on a new contract.
Mason was one of the Thunder's most popular players after playing in college at Oklahoma State and later returning to Oklahoma City when the New Orleans Hornets spent most of two seasons in the city after Hurricane Katrina. He had expressed his desire to remain in Oklahoma City after a hyperextended right knee forced him to miss the second half of last season.
Montgomery said the two sides weren't able to agree on a role for Mason, who still wants to make significant contributions.
"Desmond is not ready to be relegated to a cheerleader and relegated to a mentor for the younger players," Montgomery said. "Desmond's got a lot left in the tank."
Mason burst onto the scene as a rookie by winning the 2001 slam dunk contest as a member of the Seattle SuperSonics. He's also had two separate stints with the Milwaukee Bucks and has averaged 12.2 points over the course of his career.
He played 39 games with Oklahoma City last season, breaking into the starting lineup in mid-December and staying there until his injury in late January. He started the last 18 games he played for Oklahoma City.
"We value and appreciate Desmond's contributions to the Thunder. However, at this time it is important for us to retain flexibility with our roster as we move into training camp," general manager Sam Presti said. "This was a difficult decision, certainly not the last one we will be faced with, but at this point in time we wanted to make sure we communicated with Desmond on our thought process so he could focus on other opportunities."
The Oklahoman first reported the Mason impasse, citing an anonymous team source.
Montgomery disputed the report that negotiations failed when he requested at least a two-year contract in the neighborhood of Mason's $5.3 million salary from last season, while the Thunder would offer nothing longer than a one-year deal.
"We never discussed money," Montgomery said, adding: "It wasn't going to be a dollars decision because his heart was in Oklahoma."
Montgomery suggested Mason fell victim to a youth movement in Oklahoma City, where the Thunder have also cut ties with veterans Earl Watson, Damien Wilkins and Chucky Atkins this offseason while building around Kevin Durant, Jeff Green and Russell Westbrook -- three players in their first two years who were staples in the starting lineup last season.
At 31, Mason would have been the oldest player on the Thunder -- by about six months over new acquisition Etan Thomas, who came over in the trade that sent Wilkins and Atkins to Minnesota.
"He's 31," Montgomery said. "Desmond's still got a lot to do in this league."