Exam CCBA topic 1 question 327 discussion

A passport agency has recently deployed an online system where customers can apply for, amend, and renew passports. The expected volumes have not been realized and as a result, the agency has not achieved the projected savings. A business analyst (BA) has been asked to investigate the potential causes of this shortfall by understanding the trends, patterns. and volumes at a detailed level. What method of requirements elicitation should the BA start with?