A usually competent co-worker is struggling to write a difficult — but not impossible — report. Despite clear instructions and deadlines, he has not even started, and his delays and excuses are holding up the rest of the team.
They are growing impatient and resentful; it is time to intervene. Do you a) lose patience and write the report yourself; b) offer the dawdler advice and instruction; or c) ask him to mentor the graduate trainee?
The most obvious — and seemingly sensible — course of action would be to offer instruction. A likely reason for his procrastination is lack of knowledge: he simply does not have the information or skills to write a report: gathering facts, turning notes into prose and so on. The least-sensible move, surely, would be to ask him to be a mentor to a junior.