Well, suffice it to say that anything is possible.
However, it happened to me several times in one session of C'tis vs. Pythium and really annoyed me.
Here is the quote from Kristoffer O in a post regarding this issue (or a very similar one) that he answered in the List Game Bugs Here sticky on 1/10/04:
"It might be that the AI still remembers how to give the order 'fire at enemy commanders'."
If it was some sort of strange luck deal, it was still unrealistic for a single crossbowman to pick out one commander from literally 100+ troops and kill him in 2 shots from the start of the battle. If it is a bug, it is one that made that game very unfun.
[ January 29, 2004, 04:06: Message edited by: diamondspider ]