Change 1 Variable
Riot's balance team seems to misunderstand one crucial element of experimentation: you don't change multiple variables at the same time.
That is, if a champion is over-performing, 3 nerfs at the same time doesn't bring you a solution to the problem--- all it does it force you to revert 2 of them later because 1 was enough. Likewise for buffs.
We've seen this misunderstanding ruin the game several times, most notably during each of the class updates. It's not hard to figure out.