From what I’ve seen there’s nothing wrong with the competency of the pilots in this group. They won’t be flying aircraft into hills. A broad range of experience from international ops to Aussie GA Pilots and old school Aussie NJS Pilots (from before Cobham or Qantas took them over).
Competency will only get you so far if both power-plants decide to give up the ghost on the same flight, which is what you risk when engine failure rates start to head into multiple occurrences for similar reasons. Fair enough a bird strike, some FOD, a few unrelated events, but to have 4 core engine failures for mechanical distress in short time is worrying. All you need then is a bird to knock out one and the extra stress on the remaining for it to go pop. Hopefully somebody has had a good look over the things, as this seems worse than Tigers paperwork/systemic issues that grounded it, they were not having actual events. Combined with what seems like a joke T&C department if the 70% fail rate is accurate. But I guess NJS has documented and itemised each mechanical failure and has a wad of paperwork that CASA has checked compliant with standard operations, each sim/line check failure has a nice graph to show which area of competency the candidate apparently failed at, so it must all be OK?.