a dominant dog does not necessarily mean the bravest against a big bad boar...sometimes the meek and weaker dog can be as courageous as a good catch dog.
I am not doubting your statement at all, but in my 30 plus years (like you) of dog training and horse training most of the time the dominant animal has the most drive. I've had dominant bitches that I've culled due to the fact that they would try to fight to the death. So I'm not disputing you at all but like you I've been doing this a while and this has been my experience.