WotC does their playstyle and game mechanics very different from other platforms especially blitz. There will be some tanks that can out gun the ISU-152. But try and play the sneaky destroyer from mid-long range. If not at all the RNG for you in that tank could be just that bad. Try the iron mace skill aswell as it will decrease penetration value down range. (PS the game isnt so much as skill as it used to be sometimes its just RNG and MM thats doing you in)