what kind of bow and what pundage are you shooting? have you shot it at 10 to see how much higher it is? most bows these days shoot pretty flat out to 20. my first pin is at 20 because at 10 it is only an inch or so high.

unless your bow is on the slower side and your arrow drops quickly, it is more likely that the deer "jumped the string" causing a higher impact IMO.

some may disagree, but i always shoot low (heart area). if the deer is alert, i'll shoot even lower. if you watch slow mo's, even an un-alert deer will still drop a little in most cases. my theory is, if i shoot low and miss, the deer is uninjured as opposed to if i shoot center and it ends up going high.

it also helps a little from a tree stand since you have the downward angle... a high shot on one side of the deer will exit lower in the other side.