@RIOT: Champion Mastery Score Needs Adjustments

Okay, there are some seriously strange things going on with how the game calculates your mastery score, and now that it leads to unlocking rewards, it matters more than it used to. Please look at this match: http://i.imgur.com/JbcFjvB.jpg

Why did I only get an A+ when Poppy and Xin got S? I had the best KDA ratio in the game, I did just as much damage as Poppy, and I only had slightly less cs (because I was fighting the enemy more than farming). If Riot wants to encourage more action in the game, rather than passive farming, shouldn't the mastery system reflect that?

It really doesn't make sense. This has happened to me in a LOT of games where I felt like I performed significantly better than others.