CainIV - 7:42 pm on Dec 29, 2007 (gmt 0)

My theory is that those sites are being held by a transitional "safety net" avoiding a drop past 6 to allow a period of grace in which to take remedial action.

I am not sure this model fits well. In some cases we are referring to authority websites who are not actively pursuing and are not actively acquiring links.

In other cases such as mine, keywords where the keyword was heavily promoted are at #1 while others have dropped to position 6.