This certainly looks like the same incident we have heard of before. First or second occurrence, just "how could this happen", as has been asked by the TV talking heads? Not withstanding that DE subs are very difficult to detect and track on batteries and ASW is hardly a top priority any more, here is how it can happen. Chicom sub sits quietly on the CSG PIM for many hours or even days. When the CSG is in range of sensors and ASW assets the Chicoms are detected. After relentless tracking and simulated attacks by the imperialist dogs the Chicom sub is low on batteries and is forced to come to snorkel depth to recharge batteries. This sort of scenario hardly ranks a failure of the Navy subsurface screen. In deed, it is as good as a kill. And don't expect the Navy to defend their reputation by admitting to their ability to detect and track adversarial subs or confirm the volumes of acoustic intel that would have been gathered. Lest you tend to the Navy buffoon theory and discount this scenario as fiction I'd have to admit to living a similar fiction in another life.