Sooo... about those ranks on champion masteries...

I don't get how they work... Been working my butt off trying to get an S rank.. Several games going 200ish + cs in a 30 minute game, with 21 kills and 0 deaths, several games give or take a few figures like that, or rather "average" games for me such 180-280 cs and positive 6-10 score, with several towers dragons, and barons to my name... I'm not an "amazing" player, but there are occassional games everyday I just roflstomp everything and carry the team without questoin in both cs, kills, assists, and.. everything else, and I always only get A+ to A- rating.....

Then...

This game.. I go 15-5.. 210 cs, on a loss, with no towers, dragons, or barons, (My mouse actually died so I was out of the game for a good 6 minutes trying to find batteries) and we surrender at about 26ish minutes and I get an S-....

. wtf?!

I don't get this rating what so ever..