A good point. Given that BE is down to zero, my guess is that they've taken the oversales down a notch (since there's no room in BE to accomodate them).

Also, thinking about this more if it's close to DOD, it's possible that DL simply zeroed out BE and opened up more Coach inventory on the theory that it is more likely to sell the coach seats than BE (although that's more commonly seen on three-class carriers, closing down F and opening up J so F would only sell to 5 of 15, but J would oversell to 47 of 37 - keeping the number of premium seats constant at 52). Not sure I've seen that as much on two-class service though.

Overall, the moral of the story on OpUps is that planning for them is a sucker bet. Airlines are pretty good at predicting no-shows, so they are pretty rare going from Y to J (more common J to F).