Ya know what I think leagues biggest problem is?
I think there are too many variables. The main contributer is the amount of champions. Over 140 of them. Each having a minimum of 4 abilities. That equals over 560 abilities (700 if you include passives). That's a lot of stuff dude.
Everything known to man experiences a net gain of entropy every instant. This basically means that everything is becoming more and more unraveled and unstable. This applies to game balance as well. Each patch, each change, new champion, rework etc raises the entropy of the game. The more you add and change the more unbalanced it will become.
My advice? Slow it down. stop making massive changes all ay once. Give love taps not a fucking sledgehammer to the face. Stop making so many new champions, and think of making some more old school styled simple champions. I know flashy characters sell, but the more this game sells the worse it will get. I get people want new experiences in the game but that doesn't mean you need to completely replace certain champions with someone else (aatrox) or add new champions that have no place in league (Zoe). It's time you take a slower approach to this game. The massive speedy changes just make the game harder and harder to balance, and it is going to get worse and worse if you keep it up.
There has to be a point in a game where you take a step back and let it happen for awhile. No patches no new champions no new reworks items tunes whatever. Just let it run. Watch what happens. People adapt. The meta will still shift even if you don't change a damn thing. If people start playing assassin's more people will play tanks to counter assassin's then people will counter tanks and so on. It'll be slower but you'll see healthier changes in the meta and an overall better game. You gotta let the water settle before you make changes. Think of the game as an experiment. You don't rush and change the variables whenever you want. You have to test then and see what happens and record and analyze and then think and reflect and then replan and retry with small chabges. If your experiment doesn't work immrdiately you don't smash the test tube you wait it out and retry.
This game is unbalanceable by nature. That is accepted. however to bring this game yo a healthier state you have to slow down. Return to your roots . You're a massively wealthy company now with many many many amazing minds working for you. These creative individuals have lots to show. Make sure that they're putting out the quality content you and they know they can make and not just quantity. I don't care to wait 10 months between new champions as long as that means they have been tried and tested and are well thought out and most importantly:: THEY SERVE AN ACTUAL ROLE OJ THERE IS A NEED FOR THEM. akali and aatrox rrowks imo have no reason to exist. They don't serve any purpose in the game and both were probably better left to rot then be changed into what they are. Zoe should not exist. Pyke should not exist. They're not well thought out and they have serious problems that will make them nightmares to balance. Sure they're flashy and really REALLY fun to play, but they are hell to play against and is some cases to play with. Stop adding things that don't need to be added.
Dumbing the game down a bit is okay in some ways. Asdign a simple champion that has a place in the meta and isn't a total table flipper is okay and very healthy right now. Adding a super charged flashy chanpikn that is no fun to play against and feels antifun is not healthy.
TL;DR Make feweer changes and make smaller changes . Slow down on reworks and new champions . Think it through REALLY well before you release it. Let the waves settle before you throw another rock.