Ive finally found the Autosporrt article where the FIA tender specifies the amount of relative degredation the hard/medium/soft compound tyres must meet for the new tyre supply contract
http://classic.autosport.com/news/report.php/id/137532/
There will be three compounds at each race, as expected with the simplified hard, medium and soft names. The FIA characterises the tyres as follows:
- Hard compound: 2s degradation achieved at 22% race distance Base lap time
- Medium compound: 2s degradation achieved at 18% race distance 1.2s/lap quicker than Hard compound
- Soft compound: 2s degradation achieved at 10% race distance 2.2s/lap quicker than Hard compound
I assume something like this was written into the current tender and contract which Pirelli are fulfilling so you can't blame them for the state of the tyres - just the requirements of the contract.