Depends on the hosts. Usually you are required to be struck by a bb to be effected by grenades. Not proximity based. Some fields/hosts differ on this rule. It's vague. If in doubt, call it. Distration devices are that, a distraction, no hit call required. Some games require a mandatory "stun", which is bullshit.
Grab, throw back, kick grenades which are timed. Do it.
Ár skal rísa, sá er annars vill
fé eða fjör hafa. Sjaldan liggjandi úlfur
lær um getur né sofandi maður sigur.