Regarding key fragment drop rate

Reading recent Riot answer to key droprates question made me want to share a real life example and a suggestion.

I had around 50% winrate with over 400 games last year and around 30 mastery chests (out of around 50 possible). Still I had 6 unopened chests remaining. Which is 18 key fragments. Which I feel would require more then 50 wins (or 100 games). At my play rate it's about 1/3 of year. Which is impossible.

I don't want to say the system is unfair. I don't incline Riot is pulling money by reducing access to keys. Although I seen even high elo players saying that. This mastery chest system is good for both Riot and players but I don't want to go deep into this.

I want to point that even though system may look accurate on paper - it isn't in real life. One reason is - distribution of wins is uneven. I'm pretty sure there are more interesting statistics if you look into relative data.

I have a feeling there are more leftover chests then leftover keys for a player group that is above let's say 6 months of consistent playing. I seen players complaining that they don't have enough keys more then complaining about mastery chests. And I'm definite it's not intended to work this way.

Maybe having a more distinct system would be better?! Smth like: you can get 1st key fragment in 1st win. Second in 2 wins. And it expands further and resets every week. A distinct number of wins instead of % droprate. With a GUI bar that fills and accessible by players in client. Like "[[[[[[[[[3/5 wins]]]] to next fragment".