If I recall from physics a pass through would be energy loss. A bullet that doesn't expels all energy within.
Energy =/= injury. Soft armor completely stops a pistol round, the target absorbs all the energy, no permanent injury in most cases. Hard armor completely stops rifle rounds, the target absorbs all the energy, no permanent damage in most cases. Because there's no permanent wound channel, no exsanguination, no damage to organs.
What's the kinetic energy of a human body going 75mph and getting stopped by a seatbelt? Again, if no permeant wounding, no death. Even though the energy level is very, very high.
A bullet that exits and leaves more permanent damage behind will kill faster than something that stops completely in the animal but fragments into muscle. Bullets work by converting energy into permanent wounding - if any bullet has enough energy to create it's maximum wound channel, that's as good as it can do, whether it stops or continues to pass through. Splashing a Nosler BT into a coyote's neck vs sending a slower, lower energy bullet through it's heart ends up with a wounded animal in the first case and a dead animal in the second, even though the bullet that passed through has less energy overall, put less into the target, and "wasted" some by passing through.
There's also a flip side - placement matters. A permanent wound channel in an elk's paunch won't kill nearly as fast as one in the vital organs - splashing a bullet into it's lungs with lower permanent wounding will kill faster because there's more blood loss even from the less efficient permanent wound - but both cases result in long death times. A 300 RUM dumping half the the bullet's energy into a massive wound channel through the heart kills a lot faster than a 300 RUM dumping all it's energy into a shoulder because the bullet didn't penetrate. The animal will have a broken shoulder and not being going anywhere, but it won't be dead as fast.