The Mercury announced Saturday that the franchise and Charles had agreed to terms on an immediate contract divorce.
"After discussions with Tina and her agent, it was best for both parties to go our separate ways at this time," Mercury general manager Jim Pitman said. "Due to circumstances both in and out of our control, our season has not gone according to our plan, and we will continue to pursue all avenues for improvement."
Phoenix coach Vanessa Nygaard declined to discuss the reasons behind the separation but said it was "best for both parties" and that the team is "ready to move forward."
A source told ESPN that Charles' divorce from the Mercury had been in the making for most of the season. She had been unhappy with her role in the offense, which included a desire for more shots, for some time. Charles expected to be used in a more active role in the wake of center Brittney Griner's absence this season but felt like she wasn't given the opportunity, a source said. She averaged 14.8 field goal attempts per game in the 16 games she played for Phoenix, the fewest since her rookie season in 2010. Her 17.3 points per game this season was her second-lowest average since 2015.
Charles regularly made comments about wanting to either be traded, cut or divorced from her contract, a source said. Her divorce Saturday came together in a short amount of a time, a source said.
Before signing with the Mercury, Charles had narrowed her choices to Seattle and Phoenix, a source said, but a disagreement between the sides in how Charles would be used by the Storm led her to choose Phoenix.
After parting with the Mercury, Charles will have to clear waivers, which she is expected to do because no team appears to have the salary-cap space to pick up her pre-divorce contract. Once she is cleared, she can become an unrestricted free agent and sign with a team that has cap space to give her at least a prorated minimum salary.
One team that can is Seattle, which is considered a front-runner for Charles. The Storm have three of Charles' U.S. Olympic teammates in Sue Bird and Breanna Stewart -- both also fellow UConn graduates -- as well as Jewell Loyd.
Storm coach Noelle Quinn declined to comment Saturday when asked about Charles' potential addition.
Nygaard, speaking before Saturday's game at the Dallas Wings, said the Mercury will be looking to play more small ball without Charles, adding that she hopes the team is quickly able to find new players to fill the roster.
"The players are very focused and they are not happy with how we've been playing, and so they're ready," Nygaard said of the Mercury, who are 7-12 after an 83-72 win over the Wings. "This is an extremely competitive group. When it gets to be like this, all they want to do is win."
Charles, 33, was averaging 17.3 points and 7.3 rebounds for the Mercury, who have been without Griner all season, as she is being detained in Russia. The Mercury also have dealt with various injuries and illness in their first season under Nygaard. They made the WNBA Finals last season under coach Sandy Brondello.
The Mercury signed Charles in February to a reported one-year deal for $108,000. Charles was the WNBA's scoring leader in 2021 after averaging 23.4 points per game while playing for the Washington Mystics. She didn't play in the league in the 2020 COVID-19 bubble season in Bradenton, Florida.
The No. 1 draft pick in 2010, Charles played with the Connecticut Sun from 2010 to 2013 and with the New York Liberty from 2014 to 2019. She was the 2012 WNBA MVP and is an eight-time All-Star and three-time Olympic gold medalist. She won two NCAA titles at UConn but has not won a WNBA championship.
ESPN's Mechelle Voepel, Alexa Philippou and Josh Weinfuss contributed to this report.