What can we generalize about the relationship between tenure and return?

This is a great chart for ceo tenure and performance.See http://nicolasrapp.com/wp-content/uploads/2012/10/A29CHA.gif (Links to an external site.)

What can we generalize about the relationship between tenure and return? Is it possible the findings are the result of circular reasoning and not performance? Do you think corporate politics play a role?

Discuss from the viewpoint of top management and the best strategy for the firm. Try to draw in the associated lessons. Accomplish this with a Word document, 11 point Calibri font, single spaced. You should be able to accomplish this in 2 pages. 

Also see attachments for more information. 

CEO Tenure