From the Ask Tom mailbag:

Question:
Now that I know more about Time Span, I realize I have over promoted someone beyond their capability. What can I do to repair the damage? I need this person’s skills, but they are floundering in this new position.

Response:
You have already taken the first step. You have accepted responsibility for your dilemma. Often, we blame the floundering team member when it was our miscalculation.

Now, that you understand Time Span, your next move is to calibrate task assignments (goals) within the Time Span capability of the person. To understand the Time Span of the task assignment, you have to trace your way back to the goal. A goal is a “what, by when.” The “by when” of the goal is the Time Span of the task.

If you list out the Time Span of the former task assignments (where the team member was successful) along with the Time Span of the new task assignments (where the team member is having difficulty), you will likely see a pattern. This pattern will be helpful in determining what Time Span task assignments are appropriate.