So it seems like a lot of people are playing the blame game around where I work, and it brings up an interesting question.

Knowns:

Requirements team writes requirements for product. Developers create their own unit tests out of requirements. Testing team creates their general tests out of requirements and past customer issues.

Product released if and only if X% of testcases from Testing team passes

Customer response team gets bugs from the field, and lets the testing team know about these issues.

Question:

If the customer ends up filing a lot of defects, who is to blame? Is it the Testing team for not covering those? Or is it the requirements team for not writing better requirements? And how does one improve upon the system?