Yeah--I agree. Think about it: if there's wire between the die and coin, it's still there at the field/bust junction--and it must leave a mark under all that pressure.
The same might said about a piece of wire--I might expect it to curve a little as metal pushes it into the recesses of the die.
Actually I used to work at a automotive parts manufacturer. When you move parts down a line quickly, if a sharp point develops on the surface it will create a very straight gouge just like this one. So, to me, it simply looks like the dime was slid across a sharp point, probably when Brinks was moving them in their system to roll them.
It's got another dark mark on the right side of the rim suggesting something laying across the diameter from rim-to-rim, it just for some reason didn't take in that field. This is still a "cold case," lol.
Well...even if there are marks rim-to-rim, that doesn't prove it was a strike-through. Consider die clashes. You see the edge where the field (high part of the die) and a portrait (recess in die) meets and exerts a lot of force when it hits another die. It's the same when a die strikes a coin blank or there's an object between the die and coin--if it's struck that way, it will show.
I get it. I can't explain why the field on the right side is untouched, then. I think this calls for a special type of investigator in the CoinTalk Investigations Unit, namely, a forensic numismaticologist.
And with the field being the highest point of the die it would show the impression first. Also with the outer part of the ear being the lowest point it would be the last place to show a strike through.