I don't know if I am just now noticing this or if its just always been like this, but seems like the AI is attacking one army at a time now?

Attacking 2-3 of my armys getting destroyed then sending another army after a couple turns and letting me chew that one up

hope im not delusional but cant remember this happening that often before

I know Ai can be very dumb but remember thinking when I first started playing that humankinds was alot better than that 

In my current game I got attacked by Arjuna a couple of times across an ocean separating us. 

First time was with one army plus some prowlers already present, so basically two armies.

Second time was two armies crossing the ocean together.

I haven't really noticed anything changing in this regard.

I think the AI has some variety and how it attacks is dependant on several factors.