There seems to be a problem with the damage dealt by a ('captured') Flak 88 when firing against a Tiger. I've noticed on both Libesy and Villers Bocage that a shell hitting rear armor doesn't even make it smoke, let alone side and frontal hits. On Libesy I once hit it four times on the side and it still wasn't dead.

I don't know much about WWII balistics, but my guess is that an 88 should be well able to take down Tigers and that this was merely forgotten about in all the other development stuff. I wouldn't know why this would be on purpose.