She still falls off so hard late game, not only that, but actually HARDER than pre-rework. At least before the rework, you could assassinate squishies and return to your initial position safe, but now, once you jump in, you're screwed since you have 0.3s delay on your W before using it again.
She's never had a strong late game. Your job is to bully lane, take some towers, pick people off, roam to other lanes, get your team ahead/tilt enemies, and if it comes to late game, your job is to dive the backline and assassinate squishies and CC whoever you can in team fights. LB's job isn't to duel, or to be able to 1v5, it's to be able to assassinate any low health, or squishy champions that she can catch out, slowly but surely adding pressure and increasing her teams odds of winning the game.
The champ isn't the issue, this is a playstyle thing. But generally speaking in regards to the long gamelengths and current tank meta: most assassins are not strong picks right now (hence the 40-50% max win rates)
