I was a regular when DL was trying to make the lieflats work on that route. The only way a nonstop with lie flat seats works on that route is a redeye eastbound and 6am return. Otherwise there is no value in having a lieflat seat for that short a daytime flight, especially at the prices DL was asking back in the day. DL either a) did not understand that and/or b) the timing of the flights had more to do with utilizing underutilized a/c.