Editor X recently said his/her (we shan't reveal!) big house will use pen names for authors' whose last books tanked. Authors have long asked to use pen names— for multiple reasons (that's the juicy part, but our lips are sealed)— and pub'rs always refused. The problem was promoting a previously pub'd, maybe even known, author while keeping the ruse from booksellers. We cannot say why this is not a problem still.
We think it is a sin that a bookseller's loyalty runs only book-to-book. Steve Ross, the CEO who united Warner Bros. and Time Inc., said that without failure, you are not doing your job, which is to make things (in this case stories) new.