@Riot - Leblanc can only be countered at champ select.
Riot has said before that they do not want games to be decided at champion select. Leblanc is a champion that can only be countered at champion select. If your team has instant point and click ranged CC (Annie, Ryze, Maokai, Taric, Fiddle, Lissandra, Lulu, Malz, Panth, Warwick), then she is not even an issue. If your team does not have instant point and click CC, and she gets slightly ahead, you are never going to be able to stop her in-out pattern.
I understand that assassins are designed to go in, delete someone, and get out. They should not, however, be able to do this every ten to fifteen seconds for harass with very little risk. If you don't have instant point and click ranged CC, it is not very risky for the Leblanc player to repeatedly Q/W, as unless you predict exactly when and where she is going to w to, you can't hit her before she can instantly blink back out. Further, if you don't have any CC or damage that she is scared of at all, she can Q/W/E, and if she hits the E, she can just R to try for the kill. If she misses the E, she can go back out, and try again in fifteen seconds.
Zed just got this ability to instantly blink back out to safety nerfed, even though he was only able to do so using an ult with a long cooldown. Leblanc can do this over and over again. She should have to wait one second to return to her initial location the same way Zed does on his ult. This would provide counterplay, and make Leblanc have to make a strategic choice of whether to go in, rather than simply knowing that if there is no champion around with point and click CC, she can blink in and out with little risk.
Lastly, I want to talk about her win rate. Her win rate is low. It has always been low. It was low when she was last nerfed. Champions with complicated kits often have low win rates. This is exacerbated where the champion's strongest play pattern can be hard countered by other champions. Point and click CC hard counters Leblanc, but if you don't have it, she is terribly oppressive to play against.
Thanks for reading!