For all those wondering how Lee Sin falls off.

http://leagueoflegends.wikia.com/wiki/Armor

This is why.

Since armor is the most scaling defense in the game and Lee lacks the Zed "% of damage dealt" and Talon's stupid amount of AoE damage + invis, straight damage Lee Sin's have a tendency to get eaten the moment they jump in. And due to the nature of armor as a defense (I.E., how the math actually works), that 200% bonus AD on his ult starts to factor to a much smaller number than you'd want.

Now, if you're wondering why Lee versing an unfed team is a much bigger problem now than before, that's more likely due to the change in scaling. Since Lee was designed with a strong early game with decidedly all right scaling, the change in how scaling by level works has actually given him a little bit of a buff by comparison to how other champions faired.

So the moral of this story is probably more along the lines of "unintended consequences to balancing actions makes players quite upset".