I think a list of reasons should be available when staff closes a ticket, this reasons should be able to be updated from admin account.
the idea is that when closing a ticket, staff chooses a reason from the list, so when admin (or manager) checks the closed cases, statistics can be extracted. for example, a list of reasons could be:
A) user error
B) hardware error
C) software error
D) closed due customer not repliying a request
E) incrorrect ticket opening
so, we can extract monthly reports of how many tickets were closed due what reason.. etc.
I hope this is considered for future releases.