As an Assault spec, one task was to kill 1 enemy with a grenade.
"That should be easy" I thought.
Well, not exactly.

Enemies simply lean backward, as if they fell for surprise, stepping outside the explosive range just for inches.
That's ridiculous. Maybe once, but seeing three grenades being useless because the soldier I was attacking always managed to "show me the surprise for a grenade landing on his feet by falling down right outside the explosion area".
This should apply even more if the enemy doesn't see the grenade incoming.