The best method to analyse the current knowledge skills and abilities would be the interview method. Buy directly interview in the job holder with help of a structured interview to extract the information about the specific job from the employee can be done by an interview. By analysing different aspects of talking as well as behaviour of the employee of the job holder. Job interviewer can be able to extract very meaningful information from the job holder about his specific job and work structure.
Efficiency of this type of job analysis method is totally dependent on the interviewer and the ability of the interviewer define the level of extraction of .the information from the job holder.
I am a school teacher and I have been through such interviews for so many times after giving out interview so many times I had an opportunity to take an interview as well and apply the same analysis method for interviewing other teachers to know their overall potential and abilities. By applying this specific method I was able to extract important information from the job holders as a part of my interview. This type of analysis method gives a very accurate result and it is totally dependent on your ability to make him speak about the facts and the truth. Selection of the interview method was totally my choice and it came out in a positive way as he told me everything what I wanted to know