MVP in Leauge?????

i main rek'sai jungle and i realised that S is so hard to get. after i got her to level 5 i stoped play her bekuse i wanted rengar and darius in 5 then i found some champs that fited my playsitle so played them a bit. the level 6 and 7 came out and i of course started play reksai again. So now i got 43k mastery points and still have her in level 5 my freind main mid and have zed (30k) AND aurelian sol (26k) in level 6 i know that dont say much i mean meaby he carred me but for example one hour ago i went 10/2/11 in a 22min game. had the most kills in the game and still i only got an A -.- and remmember reksai is a tank. i have one token and that time i got 16 kills. 16 KILLS WITH A CHAMP THAT SUPPOSE TO BUILD TANK IS THAT REALLY WHAT IT SHUOLD TAKE TO GET A S- OR HIGHER. i asked my friend how many kills it takes on zed to get a s- and he answerd 15 and i was so shocked. So i want some sort of MVP thing that guaranteed a S on the MVP player bekuse in the 10/2/11 game none of the players got a S- or higher bekuse well acording to the stats i was the best player but i need like 16kills to even get a S- so nobody got S- S or S+ (i know how the system works that it compare the stats that other players whit the same mmr got on it but still i think it is unfair when you compair the difficult of getting S between the roles)