Advice related to balance suggestions:

Something I've noticed here in particular is that a lot of people seem to confuse "broken" with "strong" or "niche."

Let me give you an example of a champion who was "broken" -

Kassadin, before his rework. This champion did tons of damage, had a silence, and nearly infinite mobility. He was banned upwards of 90% of games due to his absurd strength, and his pre6 laning was literally his only weakness.

This champion was broken. A rework was absolutely necessary because no matter what the metagame, no matter what changes Riot made to summoners rift, Kassadin would be pick/ban and absurdly overpowered.

Compare this to Jarvan, who is "strong" right now -

Jarvan has an excellent early game. His clear is a bit lacking, but he makes up for it with extremely strong ganks. As the game proceeds, Jarvan loses a ton of strength due to his loss in damage relative to other champions, but he makes up for it with teamfight utility due to his knockup and ultimate.

This champion is a well contested meta pick. He has substitutes (especially in niche cases) but for the most part he fits well in every composition because the metagame is currently focused on early game power and late game teamfighting. He fits into this perfectly, unlike many other champions with strong but irrelevant kits. To nerf this champion's stats in any way would effectively trash him. This is the role he is meant to fulfill, and it just happens to be the metagame right now.

Last of all we have a champion like Tristana, who is "niche" right now.

Tristana has an average laning phase, but her midgame damage is extremely lacking despite being difficult to catch and kill. As the late game approaches she becomes nigh unstoppable.

Tristana is a perfect example of a niche pick, because without an extremely powerful supporting cast she will lose her team the game. So on a team with a very strong early-midgame composition, Tristana may do fairly well if her team can hold on while she farms out. However on a team with several late game scaling champions, you will see Tristana losing a lot of 30 minute games.

So the point of this is just to point out that we should take note of champions who are situationally strong or weak and pay attention to where they fit. I see a lot of talk about Jarvan in particular and I honestly think he's a fine champion who just happens to be playing in his perfect niche right now. In another metagame, he would be considered a niche pick like Tristana. So going to the PBE and throwing his stats and scaling all over the place may be a huge blunder when a new playstyle suddenly becomes popular.