There's something to be said for learned experience too.
Wolves spend all their lives hunting, and killing, and they learn how to do it quickly, and efficiently. And the pack structure means they fight internally a lot as well - so they are pretty experienced with fighting canine like animals.
Dogs don't spend their lives hunting and killing and would be relatively inexperienced in fighting another canines.
The only advantage a dog might have is it's health and that it's well fed. Wild wolves probably come with existing injuries and wounds, and are most likely suffer from malnutrition.
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There is certainly something to be said for combat experience.
There was an article I read above Lions vs. Tigers. The evidence shows (whenever there has been a fight) is that Lions will generally beat Tigers.
The reason is that tigers don't fight other tigers very often, and when faced with a lion, will go for the throat. Except male lions have huge great Manes protecting them - so the tigers' attack is softened.
Lions, when they fight each other, will often attack the thighs - looking to sever an artery
So the Tiger will ineffectually attack the lions throat, but quickly bleed to death from wounds.