Until someone shoots a live deer standing in an MRI Scanner(if they can scan that fast), all we can do is basically guess - or look at very limited data.
After a bullet's expanded, it would seem logical that the petals work like cutting edges, spinning like a saw blade. Assuming again the bullet goes more or less straight through the animal, more revolutions = a greater length of cut inside the animal. The more big blood vessels that are cut by the bullet's passing, the quicker it dies.
As far as launching a varmint, I shot a cottontail once with a .25-06 (before I realized they were good to eat
). It was a 120gr factory load, out of a 1 in 10" barrel. I recover from the recoil, look up, and see a patch of fur reaching the apex of its flight, about 15 or 20 feet in the air. My buddy said,
Gawd dayummmm 
We walked up and about half the bunny had simply vanished.
'sploding critters are highly non-linear
