Struck through grease or PMD ?

Hello ,

 I have this coin, which looks like it has a serious mint error .Is it a struck through error , as I believe , or is it some sort of PMD ?

 … or a weak strike … 

… or the value side was struck with a blunt object, flattening both sides in the center.

It'a hard to say with certainty because the coin also appears to have considerable wear.  “Struck through” errors are more easily determined with certainty on coins with very little wear (i.e. strong relief on most of the coin, and no details on other places)

A little more information - The coin lays flat on the table.There are no visible ( or feelable ) indentations or ding marks on it .I believe there was something - either grease or some object between the die and the coin - notice how clearly minted  the top of the 5 and the 1974 are , but the стотинки at center is missing everything apart from the с and и .

And on the back , most of the back is fuzzy , as if there were something between the coin and the die , but somethings are well pronounced - like the majority of България. If it were worn it would make sense that all the back be worn equally , wouldn't it ?