Hey Steve,
Given the punishment these boats can be subjected to, major structural failures seem pretty rare, and are usually confined to appendages like daggerboards, keels, etc... Hell, they are RACING boats, after all... (grin)
A contributing factor in this one, certainly could have been the fact that the boat was holed last year after a collision with an unknown floating object, abandoned, then later recovered and repaired... Too bad they won't have the wreckage to inspect, to determine whether the failure might have originated in the vicinity of the repair...
These boats seems pretty damn tough, to me...
best regards,
Jon