OOC:

T2K Referee
@saevikas Grenades are confusing. - I'm trying to create some player aides to help simplify some of these combat mechanics.
1. Roll MOBILITY to land the grenade in the correct place. (Extra successes do not affect the damage)
2. Roll Blast Damage based on the characters location to the center of the explosion to determine if the target gets hit by the explosion (extra successes increase damage)
3. Roll 1d6 for Hit Location to see where the blast hits the target. (Only applies if the Blast Damage roll is successful)
Reed landed the grenade dead center on the target because of the successful MOBILITY roll. Since the target is at the center of the blast radius, you need to roll 2d8 for blast damage. No matter what happens the target will be knocked prone from the explosion and be forced to make a CUF roll. If you don't roll a success, he doesn't take damage. If you roll 1 success, he gets hit and takes the base damage for frag grenades which is 2. If you roll 2 successes, he'll take 3 damage.
Two additional notes:
I misspoke early about the need to apply a -1 modifier to terrain for grenades. Terrain modifiers don't apply to grenades because your targeting the hex not the person.
Frag Grenades aren't effective against armor, so the target will reduce the damage of the blast by 2 instead of 1 if he gets his in a place where he's wearing armor. In this case, it would be his torso and head.