The Mastery Score system should be more fleshed out
In its current iteration, the Mastery Score system is so bland. It doesn't take a lot of effort to get a champion to 5th level.
Why not replace that or add the average grade they get with that champion? So if a guy often gets an S grade with a certain champion, there will be an S over their champion name.
I dunno. It would just provide a neat reward for people who are really good with a certain champion.