First, if you haven't tried it yet you can shrink juggernauts to cause them to run away to the edges of the fight the entire battle. So the AI gets them early, so what? I just shrink them all. Maybe it was intended as a joke, these big guys being shrunk and thus running away, but it really hurts the AI to not attack with them.
Second, the AI is STILL sending in lone heroes into my territory when i'm at war with them. They're easy pickings. The AI's heroes end up with so many negative traits and accomplishing little. I thought this was fixed?(Playing on challenging)
(As a side note, WoM:FE is still a great game
)