This Grading System Is Fixed (And Not In A Good Way)

I don't understand it. I have tried everything to get this elusive S, but I didn't get it!

I mostly play , and I thought I got the max mastery level, which is level 5, but the grading system threw everything out of whack for me. Like I said, I have tried everything to get a S, but that didn't happen for me. Lots of people gets plenty of S's except me. And that made me a little... well, a lot jealous.

So, I played as in the jungle, and I did all right. One time I went 11/1/1 with him, but that's not good enough to get a S. That made me really angry. I hit a big relapse and got immensely steamed again and calling this grading system rigged. Some people say I should play him in a unconventional role to get a S. So, I went for it. I used him as support and sometimes used him in top lane, but no matter what I do, I STILL didn't get a S I so desperately wanted. Even some time ago, I got so steamed that when I die too many times, I went out of control and cursed my teammates out. I got so fed up, I exited the game by choice.

And one person told me I should practice more, but I have about it too many times. In fact, I've heard about it so much, I chose not to practice at all. So, I need help. I don't know what went wrong. High kill count doesn't get me a S, high CS doesn't get me a S, even those high assists and low deaths doesn't get me a S. If none of those things get me a S, what will? I'm going out of my mind. Will you tell me what's the secret of getting a S? Please tell me. I will be forever grateful if you tell me how to get S's more often.