Position and Cache Dates

Is position affected by Cache Date changes

[frfvr]

There must be some reason for google to list the cache date along with every page listed. Is it intended to show that the page position is based on the copy that was retrieved for the cache on that particular date?

I have one cache date that changes forward to a new date on occasion, but the last time it dropped backward to a much older date and the position of the page also dropped backward dramatically in the list. So it appears to me that they are connected, maybe.

And why would the cache date change backward anyway, unless the list is now coming from a different data center, since the index is now being updated...I wish. Comments please.