ORIGINAL: GMMAT
With a higher FOC the arrow is going to be able to take the straighest path through the animal more easily than a lower FOC which would deflect much easier, losing energy along the way.
That's why I said "If your bow is tuned".
And I can promise you an arrow with a FOC of 1 or less WILL fly straight.
Once it hits the animal it is no longer flying, it is penetrating and there will be different forces influencing its path as opposed to just air when in flight.