Here is what my wishlist says for this particular book:

Divine By Mistake (Partholon, Bk 1) :: P. C. Cast
ISBN-13: 9780373802470 - ISBN-10: 0373802471 - Book Type: Paperback
Wish Date: 10/19/2008 - Your position: 2 of 71 - Wishes granted last week: 3 - Estimate: N/A

Now, I have been at No. 2 for about a month now. It simply hasn't moved --- up or down. So, how can three wishes have been granted last week without one of those having gone to me? Do they count in the "wishes granted" those books posted directly to someone's account? I'm thinking that has to be it. Which is no big deal cuz I do it myself, I was just curious if that stat was just FIFO books or ALL books posted to a wishlist somewhere?

The stat must be all copies of that ISBN posted to someone's WL, whether or not it was via FIFO.  I've noticed this on a few of my WL books I'm near the top on as well.  Enough copies posted that one should have gone to me but I haven't moved.  Has to be direct to WL postings.

I have noticed also that the number of wishes granted changes during the same week. It goes up and down and the estimate changes with it. I have one I have been at 2 weeks on for a month and a half.

Carol - I think that is because it is a 7 day look-back, not a calendar week like Mon-Sun.

Its possible that wishes granted with no change in the place in line is caused by someone coming off of hold/lost books/marked RWP by someone in front coinciding with a wish granted, but I'd say the most common reason is the posting directly to a WL. I don't think they could have their statistics easily weed out those.

how do you do a direct WL posting????

You go to a person's wish list and look for the book, then use the Post This Book option.   It will go to that person.   However, if you move to the description of the book it will post it in the regular way.