I've experienced the same results before with a couple of the sites I've worked with. None as volatile as what you mentioned but I've definitely jumped to the first page and sunk down 1 or 2 pages...
Type: Posts; User: ThirdSEO; Keyword(s):
I've experienced the same results before with a couple of the sites I've worked with. None as volatile as what you mentioned but I've definitely jumped to the first page and sunk down 1 or 2 pages...