Shades of Gray with Former Employees

It is well accepted in executive ranks that it is poor form to speak ill of a former employee.  This sin creates a negative work environment and leaves those around you pondering how they might be trashed should they elect to move on.

This guidance is easy to follow with high performers.  Yes, there are feelings of disappointment and loss, yet you are ultimately thankful for their contributions to the success of the organization.

The picture is less clear though when it comes to the mediocre and those who have been asked to move on.  While it's best to refrain from comments that could be perceived as a personal attack, there is risk in failing to acknowledge the shortcomings of a former staffer.

For starters, it potentially creates the impression that you are out of touch with the day-to-day pulse of the company.  Most workers recognize the weak links and can be frustrated by management's inability to act.
   
Granted, a termination clearly demonstrates that ineffective performance won't be tolerated.  But, what about a less than stellar employee who chooses to resign?  Should an executive refrain from acknowledging what everyone else already knows?

There is also the issue of lessons learned.  I've personally experienced this one. 

Years ago, a senior level staffer was unsuccessful managing client engagements.  This person moved on and perhaps the sole value they imparted on the organization was a collection of things not to do.

How do I share this failure to enhance our success today?  We're a small business...everyone knows who I'm referring to.

Corporate decision-making is defined by shades of gray.  It's easy to make a sweeping policy statement like "never bad mouth a former employee."  Yet, in practice, policy can be tough to follow.