I think this is more a testament to how little the quality of the book matters for the purpose of landing publishing contracts. Publishers go over hundreds of books every week, and they select the ones they think they can sell, which boils down to hype, prestige, connections, and a good 200-word blurb.

I'd say the most likely scenario is that nobody read the damned book until after they awarded the contract, and then they immediately said "wait a minute..."