Looking at the stats the game looks pretty dam balanced
over 50% of the champion pool has a 50% + winrate (including galio, urgot, sion, ve3lkoz, and even nunu) many champs the lol community considers garbage.
Now, if we look at the sub 50% winrate champs it includes highly played champs like (caitlyn, fizz, zed, leblanc, lux, ekko, and yasuo) champs people consider broken or op. If this isnt perfect balance i don't know what is.
http://champion.gg/statistics/#?roleSort=&sortBy=general.winPercent&order=descend