Grenades seem kind of odd how they are calculated when thrown. If I am reading it right when a throw misses the amount you missed by is decided by the targets AC. So if the target is extremely hard to hit and you dont roll well enough you could end up throwing the grenade so far away it doesnt hit anyone.
I assumed the rules for throwing grenades would just be an easy roll to throw the grenade into a target square, and then everyone in the blast radius gets a reflex save.
Is there a way to throw a grenade into an uninhabited square? I feel like that is how grenades work realistically. You dont need to be a pro pitcher to get a grenade in the general vicinity of a dude thats only 20 feet away, and a dude in a tank isnt going to act like a reverse magnet making the grenade launch away from himself.