I'd thought being raised in single combat and combat in general from a young age they were supposed to be pretty bad ass, they do seem a bit deficient lately really.
They were, but more so they were effectively turned into robots, i.e. they're supposed to have absolutely no fear or reservations, such as when they first showed them off and the one guy didn't hesitate to slice his own nipple off, and would have killed himself if given the command.
while this might not seem like a weakness, it can be when we consider how a healthy amount of fear can be necessary to maintain self preservation; basically an Unsullied might not consider an alternative path in an otherwise hopeless situation and thus needlessly sacrifice themselves.
Basically all fight, no flight, and that means situations where it would be better to retreat and regroup might not happen without specific commands to do so.
that being said, I think any scenes we see of the Unsullied getting worked over seem to be lazy and/or cheap writing/show production. It seems like they want a cheap way of getting the audience anxious and scared and having Unsullied be this nearly unstoppable force they've been portrayed as would deny that sensation, so they're making sure we see them getting killed off quite regularly (granted, they're doing it too much without emphasizing their competence, cheapening the impact). On the other side of it, while this show certainly isn't low budget, its scope means that it can't exactly be high budget for every aspect, and thus far the combat sequences haven't exactly been anything earth shattering by industry standards, so we're certainly not going to get Unsullied that look like the Spartans from 300, even if that's how they initially came across as.
Yeah, maybe their training was too structured and they dont adapt well to spontaneous situations. Probably just weak writing...there is no reason to think the Harpies should be this tough. It seems like they didnt even exist before Dany showed up.
yeah, it seems to me that its just the show trying to get a cheap rise out of the audience, "oh no all the super soldiers are getting killed left and right, no one is safe!!! we r so scared!"