Testing regulations have changed but very little since 2009 so Pirelli should have known exactly what they were letting themselves in for before accepting the contract.
In their 15 seasons supplying tyres to F1, there were NO similar incidents with the Bridgestones. Had overrunning the kerbs not yet been invented?
There were NO similar failures among the GP2 cars that raced on Silverstone on the selfsame weekend.
There were NO similar failures during the World Endurance Championship's Six Hours of Silverstone contested this past April, despite running heavier and torquier cars than F1.
Why should the F1 Pirellis be susceptible to a kerb damage that the GP2s and WEC cars (and the F1 Bridgestones) evidently were immune to?
According to Auto Motor und Sport, neither Massa nor Vernge had their tyres mounted backwards when they exploded.
The teams provide Pirelli their wheels of choice and Pirelli's own personnel mount the tyres on them. Pirelli personnel mount the tyres on them. The fact of the tyres being mounted backwards WAS NOT the cause of the explosions. The fact of Pirelli's tacit approval (or ignorance) of the backwards mounting might have been.
Pirelli's excuses, by and large, have amounted to a long list of "We didn't knows".
We didn't know = Failure to Anticipate/Failure to Research
Failure to Anticipate/Failure to Research = Professional Negligence