let me preface this by saying I am proud silver trash and have been since 2010. I've never really made a serious effort to climb and play too much lee sin.
Even as a Lee Sin playing silver, I have generally always felt that my games were winnable, no matter what. Rough starts, feeding teammates, and just plain bad luck could almost always be overcome by putting my head down and carrying myself or supporting whoever was closest to carrying on my team. Games in past seasons very rarely felt truly out of reach, even those miserable early game ass-blastings where the enemy team rockets out to a 10-0 lead before the first dragon dies.
Put simply, it felt like good individual play could not only stem the bleeding in a lopsided game, but turn the entire match around. Getting ganked early in the jungle was not a death sentence, bot lane dropping an awful double kill was not a death sentence, our mid getting shit on by a Talon for first blood was not a death sentence, etc.
I cannot tell you how many bloodbaths I've seen get turned around because one player on my team got their shit together and rallied the troops. Great shot calling, or a devastating initiate on a teamfight, a clutch baron steal or just expert peeling for our carry - even in those miserable routs, there was always something you as an individual could do to reliably turn the game around.
And it really does not feel that way now.
Between explosive base damage from runes and champs just being overloaded, plus the insane power spikes from items like duskblade, games are snowballing at such an extreme pace that the sheer damage numbers associated with being ahead often make a comeback feel like a mathematical impossibility.
The insane amount of damage in this game has so completely thrown the game out of equilibrium and to the point where raw skill matters far less than items and champion selection. In the past, you could win a lopsided game if your team got their act together in the second half. But these days, heroic play means very little when your entire team can be deleted in the blink of an eye.
The bounty system has only made this problem worse from mutiple levels. If a player is steamrolling and has a huge gold bounty then they become less and less likely to be killed as the game goes on. But on the losing side, a lucky double kill or good farming more times than not ends up punishing the player, since it is much easier to collect 400 gold for killing the player on the team getting routed than it is to take down the 10-0 zed boondoggling your boys. The end result is that the bounty system ends up funneling even more gold into the winning team, putting them even further ahead - the opposite if its intended effect.
Every single one of my games now is a rout - either we've completely obliterated the other team by 10 minutes, or the other team has completely obliterated us. The same dangerous champs are completely destroying any and all competition - leaving Jax unbanned, for example, is a death sentence for whichever team does not select him (and he WILL be selected). The same items and runes are amplifying the problem, duskblade, ludens, conquerer, etc.
Every game is the same, often decided before we load in. Forget skill, forget strategic comps. Whoever has the most damage outright is going to win.
League sucks now.