Check if transform is moving backwards

I'm trying to detect when a transform with a nav mesh agent attached without ridged body is moving backwards so I can apply an animation. When the player with a nav mesh obstacle attached comes close to the enemy transform with a nav mesh agent attached the enemy is pushed backwards, so I wanted to add a walk backwards animation, I tried [Here][1] but is that not world space? And I also tried - transform.localPosition But not getting solid results, any help please. Cheers. [1]: http://answers.unity3d.com/questions/123705/check-if-player-is-moving.html