Why have viewers fled from Conan O'Brien and 'Tonight'?

THE SHOW "Late Night With Conan O'Brien"

WHEN | WHERE Weeknights at 11:35 on NBC/4.

REASON TO WATCH An inextinguishable love for tall, goofy redheads who sometimes wear suit pants just a little too short.

THE NUMBERS SO FAR We've just passed the three-month anniversary of a monumental change at one of TV's most important franchises, and for NBC, there's good news/bad news.

Let's dwell, if we may, on the bad for a moment. Some 2 million viewers appear to have abandoned "Tonight" altogether, either for "Late Show With David Letterman," "Nightline" (both up in total viewers this summer) or bed. Since June 1, Conan's "Tonight" is averaging a little more than 3 million viewers, to Dave's 3.5 million. The latter is, for all intents and purposes, the New King of Late Night - if regal metaphors mean anything here - although Conan still gets top Nielsen billing among the demographically coveted younger viewers.

Meanwhile, "The Jay Leno Show" bows 11 days from today. Should Conan be worried?

THE STORY SO FAR As the army - now down to a platoon - of TV critics and writers has long known, there's nothing better than a late-night transition to keep them employed. Back in the early '90s, the "Will Dave or Jay host 'Tonight'?" story kept us cranking it out for almost a year, and thenfor another year after that, when Jay fronted a mediocre "Tonight" before the classic, muscular Leno we all now know and love finally evolved.

By that standard, Conan's "Tonight" show has been a massive letdown, because this has been one of the most seamless transitions in late-night TV history. Except for the clunky opening-night edition, nothing appears to have gone splat. Conan's a superb host with an easy, effortless feel for this gig; he's almost too good.

The show that surrounds him is up to the task as well - with usually terrific bits, like last week's "Puppies Dressed as Kittens"; a guest lineup that doesn't rely on stars/starlets shilling their latest flicks; plus, a seriously pumped monologue that now runs nearly 15 minutes.

THE BIG QUESTION Why have so many viewers dumped Conan for Dave, or the sack? Let's call it the ol' transition blues: For loyal Leno "Tonight" fans, Conan's not Jay - and Dave's not Jay, either, but at least he's not Conan. In time, they will come back. (Rememdber, you read that here first.)