For example of MF, it has some clear weakness. However, most people just don't know what it is and don't know how to counter MF.
(Out of topic, still some people build the Dominic when there's no significant HP/Armor items on enemy champs cuz people are still getting accustomed.)
I believe that the recent high win rate of MF is due to the nature of pre-season that we cannot watch any pro league game.
If MF is played in LCS and players show how to counter MF, people will learn the counter play fast and the win rate of MF would be naturally lowered.
I saw a post that once you guys nerf a champ, you don't buff it back as long as the champ works extremely bad.
As a old and big fan of MF, it would be desperate if MF gets nerf directly and indirectly by counter plays.
So please please be more patient at least by the middle of the next LCS.
There has to be some ADCs w/ higher win rates every time because GOOD PLAYERS would like to play better champs and boost the win rate.
If you nerf the high-win-rate-champs, some other would have to take the place because skillful players would find next champs and boost its win rate.
And win rate of the abandoned champ would decrease sharply by the direct effect of nerf as well as the indirect effect of transfer of skillful players.