Riot's game balance...

Hasn't been that bad, honestly. Sure, they make a few mistakes here and there, but it always rounds out in the end. For example, when Kassadin was first reworked, everyone complained he was too weak. He's a lategame tanky unstoppable assassin now that people have learned to exploit his kit. Hence, the range nerfs to his ultimate. I've even met a slightly obnoxious Kassadin player (after the range nerf) who couldn't stop bragging about how he doesn't understand why people have such a hard time playing Kassadin after the nerfs.

Lee Sin is on the strong side when it comes to mobility, and so are Zed and Leblanc. But if you take a step back and look, marksmen are strong in their own right too. They may not be super-mobile or flashy like Zed or Lee Sin, but they sure pack a punch (and there's no counterplay to basic attacks either). Take a step back and realize for a moment that League of Legends is like a big chess board.

You see that Rook over there? It's bound to devour the Pawn if left unchecked. There's not much in the name of counterplay about that. Change your strategy then! Protect that Pawn that you're going to promote at the end of the board! Maybe you'll win that way.

League of Legends is a team game. If you help your team out more and you're a skilled player, you'll climb the ladder. So ask yourself if there's anything you could have done better before considering a champion too strong. Maybe if you decided to go back and trade a little bit of your turret's health for your own safety you could return to lane in time to execute the Zed before he returns to base, instead of staying with low health and blaming the lack of counterplay as the reason for your first death.

And always remember! Riot balances with some leeway for mistakes in mind, but snowbally champions like Zed, Leblanc, or Lee Sin won't suddenly become less snowbally because of a few nerfs. If you make a mistake against a snowbally champion, that's your fault. Same with multiple man turret dives. The turret is not god, and won't protect you from four members of the enemy team when you fail to notice they're off the map. It's never been 100% safe, and never will be. So before you downvote me for siding with Riot, keep that in mind!

And good luck with League of Legends!