Eszter at Crooked Timber discusses the power of marketing:

Can this case be generalized to two similar books appearing at around the same time? Can such an outcome occur even if one of the books is completely unknown due to the utter lack of marketing on behalf of its publisher and so no one buying the hyperpublicized piece will know about the existence of the other? This blog post is an attempt to make the connection.

I think the posts’ commentors make some excellent points, the main ones being the choice of title (web term: search engine optimization) and price. OUP is the kind of press you go with if you want tenure and prestige. Simon & Schuster for sales.