When you are attempting to move out of a red zone where a cleave or AoE is about to hit, whether or not you avoid it is based on where your character is when the cast finishes and not when the animation goes off.

This will allow dodging red zones and immediately going back in after the cast but still before the animation has finished.

This can be useful for tanks or DPS that want to return to their spot quickly to either keep the mob facing the direction before you moved or to DPS.

Kind of confusing mechanic for some people because even though they looked like they were well away when the animation went off, they weren't in fact out of the the red zone when the cast finished

plus lets not forget about the .3 second server delay so even if you think your out when it goes off the game still thinks your their!