Actually the changes where not a nerf but a buff...
ISU Piercing Shot cost from 70 to 60
ISU Piercing Shot penetration now set to 1000
Concrete Piercing AOE damage from 1/0.25/0.05 to 1/0.25/0.15
Conrete Piercing AOE distance from 1.25/2.75/4.5 to 0.25/1.5/6
Main thing reduce was kill radius
It can now be used vs both hard and soft targets.
As AT it is meant to be used vs JT/Ele
https://www.youtube.com/watch?v=YmIAIzELB-M
Concrete Piercing AOE damage from 1/0.25/0.05 to 1/0.25/0.15
Concrete Piercing AOE distance from 1.25/2.75/4.5 to 0.25/1.5/6
Its lethality against soft targets tanked hard down, it doesn't matter that it will throw dust on more soldiers, when it isn't going to kill anything unless its a direct hit on clumped up squad.
And its completely ineffective against anything mobile except engine damage ele/jt, which you do NOT want to fight with ISU anyway.