[Starshine_Monarch]

In order to close the distance to their target, I've actually noticed that flying archers prefer to hoof it closer. Not entirely sure why.

Aside from that, it's possible that your archers simply ran out of ammo and the guys they dropped onto were simply the closest squad to them that wasn't already routed. I've noticed archers with ammo change their targets when the one they were shooting at runs, so it's possible that something like that happened.