It's not a matter of preference as I don't really care that much (flight is actually apart of a DTW-SEA-FAI award itin). It just seems odd that they don't have any FCM offers on a flight that is not that full. There are currently 7-day advance purchase I fares available on flight for $753.40 (while there is Z bucket open, Z fares have a 14-day or more advance purchase requirement and flight is less than 14 days out). 21-day advance purchase Z fares are $499. FCM offer on return SEA-DTW flight is $332.18. Obviously, you don't want to sell too many $332.18 offers if you think you can fill most of the seats with new pax at the $753.40 fares. But you'd think they might offer a few seats in between those two prices. At any rate, it's probably not worth spending much time trying to understand the inner workings of revenue management.