Please revert the Zed changes.
I know that there have been many posts on this website saying "Oh, Zed is overpowered! He has to be nerfed!" and Zed is a contested pick in LCS (or at least, was before the nerfs and tank meta), but please undo the changes you made to Zed.
If anything, Zed is in a spot where he needs to be buffed atm.
The Black cleaver changes hurt his build path, as it was a strong viable item on him, but now the build path for BC is so bad on Zed that it leaves him underpowered until he finishes the item. The item itself is better on bruisers and AD tanks than it is on him, without the direct armor pen.
I thought the BC changes were a nerf, but the R changes were overkill. There are many plays that Zed is now unable to pull off because of the R changes. For weeks now my muscle memory still doesn't always remember that R is not how it was - and that leads me to die where I could have lived before many, many times.
In the meta of tanks and hard CC, there is no reason to nerf an already balanced AD assassin with multiple options for counterplay (exhaust, QSS, thornmail, targeted CC, zhonya's hourglass).
Zed cannot benefit from the amazing power of Luden's Echo, which also has set him behind his AP counterparts. Zed is basically a Tier 2 / Tier 3 mid, and highly unwanted in the current solo queue meta.
Zed needs some work done on him - and you need to put time into it. The R change was a good thought, but it was not what the champion needed, at least not at the right time. It hasn't been Assassin meta for a while - and thus - killing assassins even MORE than they have been by Cinderhulk is just superfluous.
There is also no reason to nerf Zed's power so hard while keeping much stronger, and easier to play with more utility and escape assassins like Leblanc and Fizz where they are. LB and Fizz have been traditionally superior to Zed - and remain strong as they are in 5.10. I'm not complaining about them atm, but please be consistent and apply nerfs where they are NECESSARY!