I remember, in my alcohol abused brain, that the airline's policy was the use of rudder doublets, contrary to the manufacturer's advice! Also, that the pilot used full deflection rudder!
Maybe I am just a bit long in the tooth but every aircraft that I have flown has been subtley different - that's why you do a type conversion!!
Sounds like a case of "should have tried harder at school"!
Repeated mishandling leading to fatigue failure are the words that we are looking for - IMHO