I think the most accurate metric is:

[1.3(milligrams of painkiller)+.9(ounces of alcohol per week)]/number of body parts on injury report = Get Ready Its Torn (GRIT) Factor

I do not believe people are quick healers.
A tweak is medically synonymous with a tear, no matter what Holmgren wants you to hear.
Percentage of muscle bundle torn should appear in the Game Book as an official stat.
A concussion is a net positive for GRIT (you don't know you need to come out).
Ammonia capsules are underrated.
ACE bandages are overrated.
Losing feeling in your toes while icing is counterproductive.