assassins still suck in team fights.
I will say that. one example, rengar is bullshit in 1v1s and even 2v1s. he has INCREDIBLE dps because of his Q ridiculous scaling base damage but also the fact that his Q also resets his AA on a very short cooldown however just like a 1k stacked nasus which is op in 1v1s. they still stink when you group because they get focused down by ranged carries and mages and get bursted down trying to go through the frontline. the only assassin that can somewhat team fight is zed. thats about it assassins are still too risky and will not be picked in pro play. there is no reason to pick a high risk champion when you can pick a low risk champion that wins even more often. makes no sense. assassins exist in league to draw more people into the game they aren't necessary. the only necessary class in league is a support and a marskman. you can have any other combination of three roles fill the rest. assassin/tank/mage/bruiser/melee carry.
thats why they are frustrating to play because you can do so well and pretty much lose all your contribution when the enemy team starts grouping.
but somehow ad carries are the only class that is allowed to excel in duels and also team fights. at least you can outplay mages and there damages. adc like vayne or quinn. no. especially vayne.
I don't think in my over year of league seen assassins have generally have high winrates even when people were non stop qq threads about assasins rengar and zed leblanc and what not they were barely at 50% w/r