GG is 18. He's a year younger than Tatum was entering the draft. The team that drafts GG isn't going to get anything from him for at least a year and a half. Guys that young normally slip a few spots because the teams that suck enough to be high in the lottery need production sooner. I'm not sure how the Jazz feel about GG. Theoretically they should be patient enough to take him. Otherwise, he would be a typical Sam Presti or Masai Ujiri pick.
GG has the potential to be a primary offensive player, meaning, a top-3 scoring option that you'd design your offense around. So do Cam Whitmore and Bilal Coulibaly, two more guys who are still 18.