Why did Riot break Xin?

Let's make some calculation, his w heal him for 50hp +40%ap ratio (it was 70% before) and 20%ad ratio, guinsoo when fully stacked give 72 ap so 28,8 bonus healing and 54 ad + 114 at level 18 so 33,6 bonus healing. Total of 112,24+20% from spirit visage = 134,88 healing. And that's at level 18 with fully stacked guinsoo. With the 0.7% before the change he would heal like 20 hp less maybe so no much difference. don't forget that grevious wound (800 gold for ad, more expensive and not so good for ap with morellicon) will make him heal only for about 80 hp.

The crits on the third attack is useful and surely wasn't needed but most xin don't build much ad and he only crits for 75% bonus damage and it ignore devourer ghost, You don't build xin full tank, you build him like a bruiser, 2 damage item than go tanky. I agree that he don't have much counter play but so are most AA based champion in the game. xin, tryndamere, master yi, jax for me are similar and they all luck counterplay that's why riot nerf then when they are too strong at high elo