I’m guessing the rancher piled them up (to burn them?).
Asphyxiation? I don’t know - do sheep huddle around each other so close in fear and do nothing except huddle closer and then die of blocked airways because of the wool? Could be. While a few sheep on the outskirts, perhaps even “brave” sheep try to fight off the wolves but die? (Hmm - no wonder some are called “sheeple”.)
Some might have “stroked out” from fear.
Maybe.
The pack went wilding.
This is not exactly “normal” but it’s not unheard of.
I guess they could check a few dead wolves for tick born diseases but other than that, I can’t make a good excuse for this.
Sheep don’t really fight.
Bless their dim-bulb little hearts, that’s why it’s easy to lead them to slaughter.
I have a friend who raised sheep for FFA. She said they are very dumb and if afraid will crowd a fence until a bunch of them die of asphyxiation.