Dear Riot; about the new mastery system...
Dear Riot,
So far I believe this system has been a bust and will eventually be bad for business. I've been in several games where people have seen their scores, even in a winning game, and the harsh truth that they were carried and/or did poorly hurts them. So far I've played a few games as Sion in this system and have gotten a B, B+ and an A while others on my teams have gotten upset and/or raged to the point they needed to log off to cool down. It is my belief that getting bad grades on a regular basis is going to end up discouraging people from playing their favorite champions or discourage people from playing the game.
Without giving names, a player I was in a game with ( she was on the other team ) got a "D" for her score in spite of putting up a valiant effort. She had put in a lot of work for her game, even seemingly holding off our entire team at one point. To come out of the game she put so much effort into only to see her contributions were ranked "D" was simply to much for her and caused a fight with her friend who had gotten a higher grade.
I'm sure many more incidents like the above have and/or will take place and eventually contribute to the toxic attitude that many players have when it comes to their rank. While Grades are currently only visible to the person that earned them all it takes is a change of that to further divide the community. Comments like "STFU Bronze Scrub" might now be coupled with comments like "You're a shitty D+ [champion name] so don't talk to me" or the like.
Adding onto this, the fact this is titled "Champion Mastery" is somewhat misleading. With no decay possible for absent/bad playing it seems that even AFKers, players bad with X champion or players who've left the game ( and would need to re-adjust to the game and their former champions upon return ) can be a "Master" simply by using the champion. I feel with how you've set this up there is little incentive to actually play with champions for the sake of self-improvement given you've made getting the master/mastery crest sound pretty easy.
If I'm missing something please let me know, Mr. Beane.