What in the fuck happened to Kalista?

Her reasonably low damage is holding her back quite a bit, and while her passive is ok for defense, it still doesn't allow you to escape before people close into autoattack range like a true dash would, which does make her kind of vulnerable. Those are weaknesses that even top-tier players can't mitigate very well. She needs a bit more before she's a good pick.

She's difficult to use unless you're in VC with the bound teammate, and if you use her ult in a poor manner, you will actually fuck your entire team during a fight. We'll probably see her in the LCS, though, I hear Turtle has taken a liking to her.

People finally got over her damage and kiting ability, and so we're now waiting for people who actually know what's going on to master her. Once that happens you'll see/hear about her again.

The pros are going to play her like crazy. At which point all the wannabe pros will start copying them (and fail).

I don't know... Lissandra dropped off the map pretty hard when she was first released as well.

Vel'Koz was the 2nd quickest in recent memory.

turns out her passive is absolutely garbage.

Not being able to cancel your AAs isnt worth the useless dash.

And she has no offensive steroid to speak of, so even when she is ahead, she cant compete with other ADCs who actually have defensive steroids.

As somebody who played the shit out of Kalista (and sometimes still do with friends), it's the soulbound mechanic