>S- impossible on Kog Maw

I am posting this out of confusion and frustration with the mastery ranking system. I can only assume there are some metrics I am not aware of which are making it impossible for me to get S and S+ ranking. When I play a match and go 20/4 in 20 minutes, four more kills than the entire enemy team, secure the only dragon gotten in that game, force the enemy surrender... and only get an A+ I get seriously confused and frustrated. Kog Maw's global stats average 8.5 / 7.0 / 7.4 In jungle 9.5 / 7.1 / 6.9 In mid 8.0 / 6.4 / 7.1 In top 8.7 / 8.3 / 6.0

6/2/4 130 CS Mid lane VICTORY S@20 = A 24/7/9 227 CS Top lane VICTORY = S- 20/4/2 77 CS Jungle VICTORY S@20 = A+ 23/10/9 185 CS Jungle VICTORY = A 14/4/5 129 CS Jungle VICTORY = A

Performance relative to my team AND enemy team have no relevance. It doesn't matter if I put the entire team on my back from top. Let me re-iterate this for you. Several games with over double the average kills and half deaths. JUNGLE kog maw. A kill a minute. Only four deaths. A+. There is no room for improvement here. Literally the only way for me to score higher would be if the enemy team charged at me one by one without attacking for repeated penta kills.

Riot, you either need to fix your system such that extreme performance in one category can make up for another, or make the metrics of performance public. If you genuinely believe that those metrics are what makes a player good, then it can only be a positive thing to release and let people know how to be "good" players.

Edit: The game after I posted this, I played mid kog jog and got a worse score. I got an S rank. My first mastery 7 token. I looked at my after game score, and my final conclusion is that wards placed and towers taken are a very large impact, especially compared to dragons. 33 minute match - 20 minute match

http://s33.postimg.org/qj1mb9be7/Capture1.png

Scores side by side. In the jungle game, I was responsible and local to tower destructions, but did not get the last hit, but did take a dragon. In the second game, I got the last hit on two towers, took no dragons, and placed 20% more wards per minute. Despite greater deaths, less kills, less damage to enemies per minute, less kill participation, and less CS per minute, it was a 2 rank difference to get two towers and place 20% more wards.