Xin Zhao Rework almost live..Here some Math and why the new Xin is A HUGE NERF
First we are gonna Compare the Overall Burst Damage!
Old Xin zhao
With the Basic runes 8.5 AD armor/MR(or cdr) and AS and masteries 18/12 or 18/0/12 and Build
or
or
Old Xin zhao at lvl 18 would have
207 Total AD
His Q would deal
75+249Physical damage
His W would deal
480 Damage every third and heal him for 50+37+10
his E would deal
230+10AP magic damage
His R would deal
275+94+15% current hp
(All this is base damage i dont count the damages from Trinity proc and Madreds but in total burst i count it)
So his Overall Burst damage on a target with 73 armor (ADC tristana) would be 2800 damage
Now the New Xin Zhao Hiw new Q would deal 35+37 This alone you can see what is going on...but lets continue His new W would deal 70+62and 175+175all this combined would deal 482 damage if you hit them all 3 Now the New E would deal 150 magic damage His new R would deal the same And his passive would deal at lvl 18 490 every third hit and heal him for 59+27+10
Against an ADC (tristana 73 armor) he would deal
Would be 2500!! but wait if you count the fact that New Xin zhao no longer have 15% armor penetration he now deals 2200 Total Burst Damage!! So the new Xin Zhao even if he HIT his W all 3 part he lost 600 damage against an ADC...and if you count vs a TANK or Bruiser the Number goes even higher!!
And that was at lvl 18! at lvl 15 or lvl 13 or lvl 9 the old Xin zhao overall damage and heal and burst is better by even better amount because of the fact that his Thirst hit bonud damage is go up per LVL and breaks even at lvl 15 and becomes better by 5% at lvl 16..and he heals are better earlier and LATER earlier he heal 20 more per hit and later 9 more per hit!!
My suggestion here is to make his Q deal Total AD and keep the numbers the same so he can build
Or make his E deal physical damage and keep AP ratio for those who want toplay AP~! so he can benefit better from
Or make his E deal physical damage and have Total AD ratio so he can benefit from
and 
One of the 3 options would actually make his Burst almost even as the old!!! it would still be lower special Early to mid game and almost even at lvl 18...which happen very rare this days with the meta we play right now!!
The new Xin Zhao got NERFED i mean you can argue with everything but you can never argue with maths!!!
And i didnt even count the Fact that he is gonna Need to spend more Mana and Use his only Gap closer to farm in the jungle...or the fact that he lost too much of his CC because his only SLOW now its thin line on 3 part ability...
So please to the dude that its gonna rework xin zhao take 1 week more and make one of the 3 changes dont release him like that...he is weaker...and his ulti dosent justify so much damage nerf because he dosent have relaible CC any more...he lost Armor Penetration he lost Way too much ulitility and damage early to mid game he lost Overall burst in all stages of the game and all that for just a cycle on his ulti? NO Its not justified!!