Something is horribly wrong with Champion Mastery

http://prntscr.com/9jjalj http://prntscr.com/9jbyiy. There are screen shots to two very different games. Both were losses. However, In the game where i got an S-, I got less champion score than i did with the game where i got a C+. I know looking at the screenshots you might not be able to tell, but in the S- game, I got +221 to my champion score. In the C+ game, I got +250 to my mastery score. So what I want to know, is why i got more mastery score, when i did worse with a champion. Also, here are links to both games: S- Game http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2050907971/50550618?tab=overview C+ Game http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2051481856/50550618?tab=overview

EDIT: http://prntscr.com/9jln0v http://prntscr.com/9jlo4k. Heres a screenshot of the mastery score i got from my most recent game. It was the worse than the two before, but we won the game. I got over 1000 mastery score. Link to the game: http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2051483680/50550618?tab=overview