That’s how it goes. As treatments get better, more and more injuries become survivable. Because the most devastating injuries kill fastest, that also means the time in which you have to act gets smaller.
I’m passing on what my daughter has told me when I’ve asked her about this - she’s working in medical research, including some involvement on the edges of this particular piece of research.
One can evac quicker and quicker, and if the wound is a bleed out or shock, yeah, can change the stats by stopping the bleeding, and treating for shock sooner. Does less for the head shots and vaporized ones.
We have the capability to descend on the enemy with a curtain of steel and lead a mile wide and a mile deep, that can be maintained across the entire frontier.
That is how survivability is enhanced, and casualties are minimized.