It's still very early. Perhaps Milwaukee's offense comes around to make up for the defensive deficiencies, particularly on the perimeter. But I don't think there's any fixing the perimeter defense issues, which is a killer in today's NBA. But even offensively, it's still not a natural fit with both players needing the ball in their hands and Giannis being a non-shooter.
Miami was clearly a better fit for Lillard, as they could better cover for his weak perimeter defense.