I have never played a game in my 20+ years of gaming that had so many balancing errors in it.
The number of balancing errors isn't important.
The important thing with balance is the order of magnitude that separates things.
1000 balancing mis-matches don't matter if the worst offender is 0.01% stronger than where it should be.
1 balance error where something is 1000 times stronger than it should be is the thing that ruins a game.
Complaining about LoL's balance is often about blowing very minor differences in balance way out of proportion.
Champions rarely get a higher win rate than 55%. Champions often maintain a win rate higher than 40%.
What's truely bad in a game is if you run into characters like Mewtwo or Ivan Ooze where they completely dominate the roster and force out-of-game rules to allow the respective games they're in to even have a semblance of diversity.
LoL offers a very diversified choice of champions that can work at the competitive level. Every worlds tournament a solid 50 champions see play, and more in the qualifier matches leading up to that event.
The best and worst champions in LoL has a lot more to do with the Olymipcs giving gold, silver, and bronze medals and nobdy in western civilization caring who's in 4th place than it does 4th~20th champions actually being unplayable. Twitch wasn't one of the top 3 marksman everyone on the forums was whining about, yet SSW played him anyways.
Anyways - you should really concentrate less on the number changes and concentrate more on how balanced the game actually is.
LoL is, for all intents and purposes, admirably balanced - especially compared to all the games I've played. PvP in WoW seemed considerably more off, balance in DotA, Heros of Newerth, Tome, Pokemon, Team Fortress 2, Diablo I, II, & III, Starwars Battlefront II, and a myriad of other competitive games where balance matters, had worse balance than LoL.
Only game I've really played with better balance is Starcraft.