How can she put forth her best efforts when no matter how carefully she works, the item will still be defective? If no one cares, why should she? In contrast, when defects are rare or nonexistent or well explained, she understands that the management are accepting their proper responsibility, and she feels an obligation to put forth her best efforts: they are now effective.
The idea of a merit rating is alluring. The sound of the words captivates the imagination: pay for what you get; get what you pay for; motivate people to do their best, for their own good.
The effect is exactly the opposite of what the words promise.