It's not enough to write well

I was reading this interview with several editors and they were talking about how they pick books for their list. We've all heard the "I just don't feel like I would be the best editor for this book" and "I just wasn't excited enough to take this one" etc. etc… But what the he#* does that mean? Basically it means that, for whatever reason, the editor can't see himself or herself married to this book for a year or more. The commitment is huge. They have to be able to read the book a dozen time...