>they cited specific objective criteria showing that their job performance is inadequate The examples given by OP seem like subjective self-assessment to me. I

>they cited specific objective criteria showing that their job performance is inadequate The examples given by OP seem like subjective self-assessment to me. I doubt if they were that bad a programmer, they'd be able to identify such issues with their own code. It would be different if OP has received consistently negative feedback on their work, I don't know if that's the case.