S ranks Are impossible. Now this is not saying they cannot be gotten. I've gotten them. But this is madness.
I went 26/3/9 on irelia. I had the most kills by 20. The fewest deaths, the most farm in the game (133) and the game lasted 23 minutes. I got a quadra kill. What more do you want from me riot. what more must I do.
133 cs in 23mins is pretty bad. Not S worthy
Farm plays a pretty big role in ranking.
Farm is more important than the rest of the stats combined and multiplied by 58. You can have 1 0 1 score with 200 farm at 20 minutes, you will get S+
Apparently its compared to how you do against other Irelia players
Riot measures what they call "core metrics" so that, in their words, "so that if you're doing the right thing for your team, we're going to score you well for it." http://boards.na.leagueoflegends.com/en/c/gameplay-balance/bZL8vAWw-champion-mastery-qa?comment=00540000
You get compared to other people in your region who played the same champion as you in the same role as you, the higher your score amongst these people the better your grade will be. https://support.riotgames.com/hc/en-us/articles/204211284-Champion-Mastery-Guide
Also, there are a lot of people giving false advice, a lot of people believe that kda and cs is somehow a direct factor in your grade. These people are most likely wrong as it has been observed that a player can have a pretty terrible kda and cs and lose the game yet still achieve a S level grade. http://boards.na.leagueoflegends.com/en/c/gameplay-balance/cTJF3oUc-s-on-feeding-trundle
Riot has also noted that even the best of players cannot consistently get the highest grades (though they do get them more often), which leads me to believe there is at least some degree of luck involved.
The true workings of the system are unlikely to ever be revealed to us, so the best you can do is just doing your best and not worry about it. Good luck.
Help securing objectives like towers, inhibitors, dragons, barons and so on
Should have 160-180 farm around that time for the most part.
Screw riots algorithm, farm is not the most important part of a game, just like kills arent, and they need to tune down the farm stat in their scoring because Ive seen so many champs stop contributing to the team because to get an S they have to farm even though they are well ahead and team fights would win us the game... and they should account for how well people are playing your champion against the enemy team lane match ups
133 at 23 minutes isn't good.
