All too often people talk about champion balance and don't consider the player (the summoner? do they exist still?). The skill level of the player, or roughly their rank, have a profound effect on what's balanced or can be balanced.
Good read... but a large reason for that is because there are a lot of unknowns to factor into this as well. If you look at winrate vs games you often see something weird happening. Go to champion.gg and look up azir, his winrate is all over the place when compared to games played. Do you suddenly get worse after your first 5 games (a lot of champions have a dip there)? Well you might have gotten into auto pilot mode by then and not react as well as you could. Then there is a large dip at 50-125 games again. This is likely due to low number of games played so statistic is unreliable. We can also check annie, a relatively simple champion to play. Her winrate suddenly drops at more than 50 games played. Did she just get worse? likely not. Those annie players simply just play her into everything instead of using her as a counterpick. So suddenly her winrate drops since she gets played against champions she is not good against.
In the end thing is: riot is the only place with enough data that can be datamined to a precise enough degree that you can draw any real conclusions. Without that you are simply looking at data and making questionable assumptions. Sure some of those can be good but not always.
