S+ plays

ive been maining jinx a lot recently, and ive got some good games but no matter what i do i can hardly get an S- play, let alone an S+ play. I ward every time I have one, I'm always ahead of opponent in cs, sometimes double, and typically can get good kdas. I even had a perfect 10/0/7 before the enemy surrendered.

how on earth do i get an s play. i cant level up jinxs mastery and its driving me insane. always just an A