Giannis deserves a sapphire. Demarcus Cousins is not as good in my opinion and he got an 84 sapphire.
Middleton- 80 at least
Westbrook- should at least be an 88 or above
Giannis- maybe an 87
Ray Allen- 86
Paul George- 84 -86
Blake Griffin- 83-85
JWall- 85 at minimum
2K needs to have low base card ratings so they can be raised throughout the year. That's why some ratings are questionable in the game.