Lee Sin is barely a middle of the pack jungler currently. There I said it.
Lee Sin hasn't been the best option since the season 5 jungle rolled around. Lee Sin's win rate has plummeted to a steady 46%. And no, its not "because he has a high skill cap so low ELO players ruin his win rate". His win rate floats right around 46% all the way through Diamond. Here's his problem. He has a small window in the early game where he is strong before his high base damages start to fall off in the mid game. If he isn't successful in using this window, he falls off hard. He becomes a glorified damage sponge in the late game with an occasional #LC$BIGPLAYZ kick that gets himself killed almost everytime anyway. Other champions have the same window in the early game, but are much more useful in the mid to late game. Nidalee is superior to Lee in pretty much every way.
There are many junglers that do the job of disrupting the back line way better than him I.E. Vi, Jarvan, WW, Fiddle, Sejuani, etc. All of these junglers also have a better clear than him which is very important because the season 5 jungle is much tougher and repeated nerfs to machete in both price and stats have really taken a toll on a lot of junglers. A lot of junglers that are doing so well right now are only popular again because they can actually survive the jungle effectively. Jarvan had his bonus armor and decent clear (his winrate has dropped below 50% since the removal of his bonus armor by the way). Vi has a great clear and her passive shield. WW can keep himself topped off without potions. Fiddle never needs to back while he has mana. Has anyone every wondered why these junglers became so popular again overnight when season 5 rolled around? Its because a bunch of junglers struggle in the new jungle. Frequent backs and extra gold spent on a ton of potions put them at a severe disadvantage. Especially when Lee has poor scaling into teamfights/late game
Another problem that Lee Sin faces is that he just isnt that great in the high mobility meta. Do you know how difficult it is to land a Q on a mid/late game Kalista? Or Katarina? Or Ahri? Or Leblanc? Or Kassadin? Is it impossible? No. Is it easy to dodge his Q on such high mobility champions? Yes. People are always so quick to point out his early game strength, yet neglect to mention his mid/late game scaling is horrible if he's not snowballing. There are a dozen junglers that are ten times better to have than Lee in team fights.
His damage only scales with bonus AD as opposed to flat AD scaling. This means that he has zero damage scaling while he is building the tank items that are necessary for a bruiser while most other champions innately scale better with their flat scaling just by leveling up.
There is such a fuss going on about 'kicking Veigar while he's down' yet everyone wants to see Lee Sin nerfed into oblivion when he's in a worse spot than Veigar was. Why? Because Lee is used in the LCS? Even though that between EU and NA LCS he has a record of 11W-19L? Is a 37% win rate in the LCS and terrible SoloQ statistics really a sign that a champion warrants nerfs? Should we really just gut his entire kit because that time he ward jumped over a wall and got away? Or occasionally makes a flashy play with his ult? If you take away Lee's utility he's left with nothing.
So can we all take a chill pill? Lee Sin is not really a problem currently. I don't think he will be much of a problem in the near future either as RIOT is working on making jungle bruisers less viable. Emphasis on 'less' viable, not make them completely useless. A bunch of junglers that offer way more utility to a team are going to be buffed next patch and I doubt Lee will be able to keep up.
