Flying units attacking rear ?

[Nephelim]

Originally posted by Psitticine:
The mechanics are that, essentially, the unit must pass a check to bypass each unit and keep moving further back. The more units within range of their passage, the less likely it is that they'll reach the rear row.

What's the logic behind a flying unit needing to do so?

Would they mistakenly believe that -this- unit is the Last unit? I assume that units can see the entire battlefield, especially when airborne.

Is it a game-mechanics thing, so that a bunch of flying units aren't immediately a mage-killer?