Provided you've some relationship with this person / they feel free to speak I would try to get them to speak in a more open ended manner about the job and their experience.

Personally I find when folks ask me specific questions about my job ... we don't have a common language and I have no idea what they really mean by what they're asking.

Also be open to the idea that this was just bound to happen and it is nobody's fault. Some jobs just aren't for some people depending on any number of factors.