Well from my observation when see all games, IMO
S : SEN
A : TL, FNC
B : VKS, V1
C : CR, X10, NU
D : KRU, SHK
I give SEN solo S because they're undefeated at all games.
While FNC play so good, I wanna give them A+ but since no A+, I think A should do for now.