"Why did ABC really introduce in the wee hours the first Nightline without Ted Koppel since 1980?," Gail Shister wonders, referring to its 12:45am start time following Monday Night Football.

One theory "says that giving Nightline a 'soft launch' lets the new team get a show under its belt on a night when fewer people -- and fewer Nightline regulars -- are watching. Also, it makes for a kind of symmetry. Koppel's finale, last week, was on a Tuesday.

Conversely, ABC owner Disney would love to give Nightline's time slot to a more lucrative entertainment show. A weak debut from the news division would strengthen its argument."

Mediaweek analyst Marc Berman says: "It's better to premiere a show in its regular time slot, particularly in late night. You want to create an immediate pattern with viewers. They may not find it the next night."