Corporate governance is supposed to hold management accountable. Slack in the mechanism enables not only a lack of managerial competence or ethics, but also an ineffectual board. Unfortunately, whether by proxies or connections—or just sheer power—a board’s chair and other directors can remain in place in spite of having failed to hold a management accountable. Put another way, it is not necessarily enough that an incompetent or unethical management (and other employees) is removed; replacing the derelict board may be more crucial and yet even more difficult.
The full essay is at "Wells Fargo Stockholders Retain Board"