We had one of those a number of years back... 10 years as a computer operator and MCSE.
For every 4 hours of work we could get out of him, it took someone 8 hours to write up what to do and how to do it. The guy struggled with cut and paste. He did braindumps and passed exams, then lost all information within a week.
(10 years as a computer operator, typing in information, never leaving the one program he was supposed to work in)