Question Regarding Ignition Wires

My car developed a roughness just off idle that got progressively worse until it was a definate miss. It started right when I put a new carb on so for the past couple of weeks I was chasing that until I ruled it out.

I ruled out internal engine with a compression test so looked to the ignition. I had a new set of Moroso Blue Max spiro core wires on the shelf so I decided to give it a shot and sure enough the engine is now running great.

Now for the question; The wire I removed were Accel Super Stock 8mm Radio Suppresion wires (conventional core with out the sprial wrap), less than 5k miles on them. After I got these off I decided to check them out and the all ohm'd out in the 6-9K ohm range right where they should. My question is what could have gone wrong with these wires? Two of then runn near a header tube but have a fiberglass sleeve on them.