All the issues with mage->sorcerer are already discussed in multiple topics + discord Mage channel. I am very sure that the devs are already aware of mage->sorcerer issues/problems overall and in particular with most skills+skill trees and passive tree nodes. Even in the channels shown above there are good suggestions on how to improve the class overall. I am just trying to express my opinion on the matter that the things they did to mage->sorcerer class somehow leaves it in more or less in the same position. Buffing something nerfing something and the class stays nearly in the same situation overall. My point of view is that the changes from the last few patches strictly speaking about mage->sorcerer are not pulling the class from the not so good situation/position that is right now and it is possible to make the situation worse.
Of course it is possible that i am wrong we will be able to comment/discuss it more objectively/accurate once the patch is live and we test all those changes properly. For now all we can do is speculate. Although the worries i had and expressed about desintigrate that it wont be viable looking at its skill tree before 0.74 went live turned to be quite true which reside in another post and can be checked.
Bad/low base/overall damage on skills beside fireball/volcanic orb/meteor. Bad/horrible skill design/mechanics/functionality overall(especially compared to how good avalanche is performing in direction of how the skill work mechanic/design/functionality wise - not speaking about dmg here). To many x% increased bonus of something with too big y% reduce of something else skill tree nodes. A lot of skill tree nodes not making any sense at all. The situation in which you are forced to take all increase 50% damage + increased 50% mana cost points just in order to do normal/somehow ok damage which brings skill costs to 50/70/100+ basically forcing you to play with Focus skill mandatory with a special skill tree node just so you can sustain casting your skills.
Passive tree… oh Passive tree. So many nodes improving freeze rate/chills and stuff like this while they become quite useless at monolith of fate 70/80+ and arena 250/300+(this is in case we are using the current freezing chance formula). Not a single ward retaliation nodes in sorcerer tree. Not a single node improving BASE DAMAGE of spells. Overall weak +damage nodes. Bad->horrible 2 last tiers of passive node trees(the top ones). Very weak cooldown reduction last tier node (taking in mind the current formula of CDR). I am sorry i dont have the time to give the feedback skill by skill/skill tree by skill tree node/Passive tree node by passive tree node. But i think you can get the overall idea where/what the issues are.
Sorry for going a little more off topic with speaking about mage->sorcerer overall performance.