I'm a Spanish SAR pilot with offshore experience.
IMHO what led to the disaster was the human factor, with no doubt. Wrong procedures (200 ft over the sea at night, OMG!!!) and perhaps some lack of training (low recent experience, no local familiarization...). I see from some photos that at least the captain had transitioned from the "old fashioned" Sea King to the "state of the art" S92. This represents a huge leap in terms of technology and it's not easy to adapt to the new machine, I guess. So, if we talk about crew experience, we should have this in mind. Long experience but not so long in the type.