I must have terrible luck, both times I’ve caught one, he’s been in huge mobs. So, I’ve had to fight the mob off and sprint away to catch up to the goblin, and he keeps rotating to more mobs. Takes a few minutes for me to pin him down long enough to kill.
TBH, unsure of what the sack size was, but that’s good information to know, thank you. Currently, I’m at level 50.