Elephant UU in general are more team game units by design, look at the fat cost associated with them, coupled with the fact that they are made from a castle. but if you can mass them up they can do some very good work, Viper recently played a team game where his team was basically beaten by TheMax, practically alone, as a pocket Persians going war elephants.
but yeah if you can get EA up in decent numbers they are a very real and scary threat.
watch the fight at 26 minutes, then realie that all those pikes and swordsman that they just chewed up? Malians, which get extra pierce armor.