LoL grading system is not working!

Riot should rework the grading system, many can get an S+ with a score like 11/4/2 and my friend can't get with 27/0/14! () Prove: https://postimg.cc/image/5iofalbbv/

Does it depends on the champion so much? Why is it so special on some champions? Is Ornn the hardest champion to get S? #RITOPLS