See, that is something that I just can't wrap my h

See, that is something that I just can't wrap my head around...how is it that the MM's are able to do that? Mathematically that makes no sense whatsoever (yes, I know sense and mathematics are out the window where the market is concerned). How is it that the PPS dropped 10% on such an incredibly small sell by comparison of the large buy where the PPS barely moved at all? How do the MM's manipulate it to such a degree?

Thank you!