The secret to Mastery

So recently I have been struggling with mastery. I have really been trying to get higher rank mastery on my level 5 champs so that I can get the new banner and emotes. I have made some other posts on the forums discussing what things helps you get an S in a game. A lot of people have said buying wards, dying less, and more CS. But thanks to playing with one of my friends I think I have finally figured it out. The one true way to get an S is to just farm farm and farm. In the above pictures I was playing the Kayn my friend was playing the Fiora. In this game Fiora got an S and me as Kayn got an A. As far as KDA I was slightly better with 1 less death, my vision score was also better and I out did him on almost everything other than CS and damage. But I have made other posts that show that damage doesn't make much of a difference in determining your grade (https://imgur.com/a/J6UKY) the velkoz game. So apparently if you want S grade for mastery for anything other than support just focus on farming not being beneficial to your team with CC or wards just CS.