The blade manufacturing defect was estimated to produce a fatigue failure in the spar after 100,000 hours. This was based on the blade tang touching the spar for which there was no evidence in this case. As the blade was lifed at 37,000 it would never have been a factor without the strike. So I would say that the loss of the blade was due to a lightning strike compounded by a manufacturing defect. Which ever way you cut it the end result was the same.
What this and other incidents seem to point to is that aircraft design is basically sound but manufacturing and maintenance do not always achieve what the designer intended.
On the subject of false alarms the system went down last week giving a false indication and a number of aircraft were idle for no reason.