Your current approach towards balancing this game is just ridiculous.
US$1.6 billion net worth (2015 estimate) (Probably much higher now i imagine)
A cluster fuck of unintentional buffs given directly to annoying AD carry / users. And that's stacking with the overwhelming damage creep that's still lingering in the game. But i am guessing the mula must stack huh ? you wont ever hotfix it you will leave it until the community feels like drinking bleach itself 2 - 3 patches later at the expensive and luxury of skins that just happen to be one of the two most impacted champions 
from the lethality buff. These champions were not screaming for help or anything yet you buff lethality. As a company you have the power to rewind time with hotfixes.
To think that even with PBE we still get these unwarranted changes That itself makes me question what the hell is going on in that building you all work in
By the season issues should be cleared at a faster rate. You acknowledge the problem and simply revert it and then readdress / reapply it in the next patch or the next PBE cycle. This is a much more efficient way of balancing you save everyone the headaches and buy time to bring back what you wanted to bring in a more mature developed fashion. The same way you take time with upgrading game content itself should directly applied to balancing itemization / champions.
It should be that simple nobody is perfect and if there has been any case of a gaming company making mistakes i think of two companies
- Jagex but that's a different topic.
- Riot games
So your not perfect boohoo you want the player base to be happy yet you provide bleach drinking equivalents in change then refuse to revert the problem until months later. Just fucking accept responsibility and change the pace at which you address these problems. If you have another ongoing project ? or deadline regarding something else in the way? then that's much more of a reason to revert something right away when its a recognized mistake.
Hire a new team or shift some workers around into a new team that focuses SPECIFICALLY on failed implementations from new patches and give them the power revert something and fix it right away. When they aren't focusing on any recent deployed patch, give them permissions to move their eyes over to PBE to make sure whats to come wont bring anything negative that the first or 2nd pair of eyes seemed to amiss.
The approach you take now is unsatisfying Its time you stop evolving the game and evolve as a company.