Talking about balance
There is this Reddit post that mentions what is considered OP or underpowered. I don't think he truly understand how much is something overpowered or underwhelming and useless. Right now there are many OP champs: Poppy and Darius top. Lee Sin jungle, Ryze and Syndra mid, Caitlyn adc and Zyra support. Now next patch might deal with this properly, however some champs truly deserve a major rework. For example let's take Dr. Mundo. The champion has been released in 2009, hasn't received any major changes and is currently outclassed by a shit ton champions, some not even designed to be played top lane. http://champion.gg/champion/DrMundo/Top
The biggest issue would be 800g item called Executioner's Calling that applies 40% reduction on his passive and ultimate ability. Safe to say it even diminishes Q on hit health return. I wouldn't say that some champions just need to wait for the next patch, there are champions that are fundamentally underpowered.