Forced to spam control wards in spawn just to get an S rank? Please fix your broken mastery system

Two games in a row now I have been cucked out of an S rank because I was playing so well that I didn't need more than my first control ward. 6/0 194 cs 4 tower kills and a dragon solo enemy surrenders at 21 minutes S-. Second game 6/1 174 cs vs a much harder matchup, 5 tower kills, a triple kill that forced them to surrender at 23 minutes and I get a fucking A. Is it my fault my first control ward that was useful to me through the whole game was never cleared by the enemy?

I find it absolutely ridiculous that you base these ranks on arbitrary stats that are invisible to us forcing us to guess at what the fuck you want us to do. I completely dominated both rounds securing top scores in every single stat expect I didn't spam enough useless control wards. I guess from now on I'll just buy up ten of them in case the enemy decides to surrender and spam them all before the game ends so I can beat your stupid system.

[zombie-brand-facepalm]