Per Jeff McDonald of the San Antonio Express-News, Fields had been the Toros general manager since Sept. 2019.
Austin notably graduated numerous members of its team to the NBA club this season, including Lonnie Walker IV, Keldon Johnson, Chimezie Metu and Drew Eubanks.
Johnson, a 20-year-old small forward, shined during the seeding-game portion of the 2019-20 season, posting 14.1 points on 63.8 percent shooting (64.7 percent from three-point range) and 5.0 rebounds in 26.1 minutes per game.
Fields' eye for helping developing players achieve greater heights may have played a role in the Hawks hiring the ex-Stanford Cardinal star. He spoke about his "developmental mindset" in an interview with NBA.com's Keith Schlosser last May:
"I like to consider myself one with a developmental mindset. That doesn't just apply to my job or the G League, but who I am as a person. That's how I operate. I don't just love player potential, but human potential and seeing it to its fullest potential.
"I love empowering and helping players build a vision with our staff, and then leveraging all the resources I can. I'm absolutely still learning how to do that, but personally, it's always been something I've gravitated towards, becoming and optimizing.
"There's going to be a pathway that you're not going to expect. There are things that come along that you can't see unless you go through it. But the beauty of our staff is we know what it's going to be like and we just want to partner with the players to help them get to where you want to be."
That could make Fields a great fit in Atlanta, which features a very young core that includes 21-year-old Cam Reddish, 22-year-olds Trae Young, Kevin Huerter and De'Andre Hunter and 23-year-old John Collins.
Atlanta will also add another young player to the mix with the sixth overall selection in the 2020 NBA draft.
Fields joins a front office that includes president and general manager Travis Schlenk, vice president of basketball operations Rod Higgins and vice president of salary cap administration Michelle Leftwich.