Eh, there's many ways to impale people. Vlad's favourite rectal entry is just one version - judging by the reliefs the Assyrians for example hoisted people up by the ribcage, and I've seen it mentioned the "barbarian sacrifice" version usually involved digging a hole, sticking a spear upright in it, and tossing the sacrifice onto that - obviously every now and then there'd be a miss (especially if the priest-type dude doing the job was getting old and infirm one suspects), or the offering would only receive minor injuries.

Betcha such fumbling also reflected ill on the priest guy...