I have always thought that the liberals might have been foolish to resist Miers because they weren't likely to get a softer, less conservative candidate.
Following on this thinking -- with respect to your "help me out with the conspiracy theory!" plea -- maybe the play was to pretend to be accommodating by withdrawing Mier as "not a robustly qualified candidate" and then providing a "robustly qualified candidate" who is strongly conservative?
I didn't know much about Miers so didn't feel strongly one way or the other. I had heard she was an "originalist" -- meaning one who favors interpreting the constitution by trying to adhere as closely as possible to the original intentions of the founders (the idea being, if some portions of the constitution become outmoded the constitution can be amended to fix this outmodedness) -- and I welcomed this. I guess I would be happier if a different originalist having stronger constitutional credentials were nominated. I also would like someone who is outspokenly pro-second amendment, but that is probably too much to hope for.