You are missing at least two things, when a bullet goes into or through an animal, many times the hide slips over the hole(s) and there's little to NO blood loss. In my case, the bullet did exit and there was NO external blood loss for over 50 yards...
What controlled expansion means, is exactly that, controlled expansion, it doesn't mean that ANY bullet that expands and holds together will exit, not by a long shot! In fact, many times an expanded bullet that DOES hold together has less penetration, and that's why I like NP's. The nose of an NP blows off creating a lot of damage and the back 2/3's of the bullet that's left, has little expansion and goes on through...DM