There's definitely still a role for GR3 in the NBA. You look at Harrison Barnes, Kawhi Leonard, Jimmy Butler... that's what his role will be. These guys don't create much offense either, but they play great D, rebound, hit open 3s and they're valuable pieces to great teams. GR3 can play that role very well + be a monster in transition.
IMO we'll be better as the season goes on but initial impressions are that this team tops out as a good-but-not-great outfit, probably a ~7 seed or something.
McGary is far from where he needs to be due to his injury. GR3 is injured. Derrick Walton is a freshman starting at point guard. Zak Irvin is a freshman and looks like it right now.
That's a lot to overcome. The good news is that Stauskas is a monster, LeVert is much better and the 4 mentioned previously will all get much better as they get healthy and/or more experienced.