The phrase "having the right stuff" usually refers to having the necessary qualities or attributes to succeed in a particular task or role. Antonyms for this phrase could include "incompetent," "unfit," "inadequate," "incapable," or "unsuitable." These terms suggest a lack of ability, skill, or preparedness, which could prevent someone from achieving their goals. It's essential to identify the opposite of "having the right stuff" because it highlights the importance of being qualified and ready to take on challenging tasks. Whether it's in the workplace, sports, or any other area, being able to demonstrate competence and expertise is critical to success.