I still believe that Champion Mastery should decay over time.
I'm pretty sure I made a post about this quite awhile ago, but it was downvoted into oblivion. But after looking at my champion list.......I still believe this.
For example.....I have Mastery lvl 4 on Fiora; 13,948 points to be exact. However, I can't even remember the last time I played Fiora. If I'm to take a guess, it was probably a few months after her rework, and I haven't touched her since.
My Mastery Score does not adequately show my mastery over this champion. If I am to play Fiora one day, my performance would not equal that of someone who has put in the time recently to get that amount of Mastery.
That being said.......I do also believe that the higher your mastery rank is on a champ, the longer it should take for your mastery to decay. Gnar was my very first Mastery 7 champ, my most played champ in both season 5 and 6, and he was also the highest mastery champ I've had for a really long time until Ashe finally overtook him sometime earlier this year. I have 111,152 mastery points on this champ, and even though I don't play him as much anymore, I can still hop on my favorite little furball and kick some ass with him. The amount of time I put into this champ still allows me to be extremely familiar with everything about him, and it will take quite some time before I feel that Gnar is no longer familiar to me.
So, Mastery should be like this: say you have a champ at only Mastery lvl 2, but you haven't played that champ in roughly 6 or so months. After that time, your Mastery should decay at a certain rate, maybe 10 to 20 mastery point per day, until eventually it goes back down to Mastery lvl 0.
But, on the other hand, lets say you have a champ at Mastery lvl 7. Your Mastery should not start decaying on that champ until it's been like 2+ years of not even touching the champ, and even then, the mastery score will decay slower than if the champ was at lvl 2, maybe around 2 to 5 points a day.
With this kind of model, my Fiora mastery score (for example) would have started decaying a long time, and likely would have reached maybe mastery 2 or even lower by now. However, my Gnar mastery wouldn't even be close to start decaying since I did play a couple games on him earlier this year.
I just want Mastery to better reflect the amount of time someone has put into a champion, and if they haven't played that champ in quite some time, the mastery score should also reflect that.
TL;DR
Mastery Score should decay depending on how long it has been since you last played the champ, but also based on how high of a mastery you have on the champ.
