Critical and/vs. sales success

       In Raise Your Hand If You've Read Knausgaard at The New York Review of Books' weblog Tim Parks wonders, among other things:

Is there any consistent relationship between a book's quality and its sales ? Or again between the press and critics' response to a work and its sales ? Are these relationships stable over time or do they change ?

       Basically, he seems surprised by what seem to him -- given the press-raptures and (relatively) wall-to-wall coverage -- the rather middling sales figures for the US/UK editions of Karl Ove Knausgaard's My Struggle (see reviews of volumes one and two). UK sales have (according to Bookscan, which doesn't capture the whole picture) "barely topped 22,000 copies", while US sales: "stood at about 32,000". (Those seem like solid numbers for 'literary' stuff of this sort to me, but, hey, I know nothing of this industry and what might count for success, sales or otherwise.)
       Unfortunately, Parks begins his argument with a rather big mistake, claiming, re. Knausgaard:

A search on The Guardian website has ten pages of hits for articles on Knausgaard despite the fact that his work wasn't published in the UK until 2012.

       Obviously, Parks didn't bother looking too closely at those results, or he might have scratched his head why, in that case, Salley Vickers was reviewing a translation of a Knausgaard novel -- A Time To Every Purpose Under Heaven -- on 7 November 2008. Oh, that's right -- because Portobello Books published that in ... 2008.
       [I know this was a summer weekend post, and presumably the whole NYRB fact-checking crew is out in the Hamptons or something, but come on guys, that's something you catch by checking ... well, anywhere, even just on Amazon ..... Worse yet, in the next paragraph two author-names are misspelled -- it's not 'Jostein Gaardner' (Jostein Gaarder, maybe ?), nor is it 'Stieg Larssen' (Stieg Larsson). Look, I know I probably average at least one typo/slip per post, but I do this by myself, late at night -- and I'm considerably more underpaid for my troubles than even the interns at the NYRB; surely such sloppy copyediting is unacceptable for such a site, and reaching an audience of this size.]
       So, yeah, credibility quickly shot there .....
       Still, Parks does raise some interesting questions -- and does offer some interesting Bookscan-number-reveals (I wouldn't have thought Salman Rushdie's Joseph Anton -- better than any fiction he's published in ages -- would have shifted: "just 7,521 in hardback and only 1,896 in paperback" in the UK).
       I guess what surprises me is Parks': "impression of huge and inevitable success" re. Knausgaard. Despite closely following the often breathless coverage, I have never had this impression. Knausgaard seems to me a specific kind of small-scale but intense success -- see, for example, the video of the line of people waiting for his recent McNally Jackson appearance. Impressive, certainly, but also relatively clearly circumscribed. Surely it's always been hard to see Knausgaard as any sort of potential mainstream-US/UK success -- something that the coverage actually seems to reinforce, as it focuses (near-relentlessly) on a relatively narrow reading-demographic.
       Surely, also, Parks is going overboard with claims such as:

Meantime, since most newspapers have gone online and many have their own online bookshops, a certain confusion seems to be developing between reviewing and sales promotion. Bestseller lists sit beside reviews on every webpage, as if commercial success were an index of quality, while one can often click on a link at the end of a review to buy the book.

       I understand his concern that: "bestsellerdom is rapidly becoming the only measure of achievement that is undeniable" -- consider just The New York Times Book Review's pages and pages of (supposed-)bestseller lists. Still, while I would love to see actual, hard sales numbers (i.e.: copies sold), any sort of reliance on bestseller lists would serve rather little purpose: knowing that the NYTBR list this week has a book by someone named Brad Thor ahead of one by Catherine Coulter, with the ubiquitous co-written James Patterson at number four ... yeah, that doesn't have anything to do with my reading (or, might I suggest, with literary discussion of any sort -- other than of the turnover/sales-figure sort).
       I have to admit to not really caring: there are books I review that I wish would reach more readers, but I think it's pretty clear from what's reviewed at this site (see, for example, the most recent reviews) that sales-success -- potential or actual -- doesn't really figure in what I cover.

       (Addendum: of course, sales numbers do matter -- especially to publishers, many of whom care, to varying degrees, predominantly about the bottom line. So it is scary to see 'services' like Next Big Book, which promises to analyze: "social, sales, and marketing signals to help you make smarter, braver decisions" (shivers down my spine !); see Doireann Ni Bhriain on The next big thing in books .....)