the elephants are just a small mistake that apparantly sneaked in. The defence points (armour + def skill) of the riders and the elephants themselves accidently got switched.

The way elephants are now, is not our vision nor our intention or a product of a bad stat system. It's just a small mistake of a modder who worked his pants of on more than 400 units. You can imagine that some errors sneak in. Unfortnatley this is one is rather noticeable.

This issue will be addressed in a next version, a patch or hotfix (whatever will be released first). Also it's an easy fix just swapping the values in the EDU.
If needed I'll write a how to on it.