In moving Diane Sawyer from GMA to World News Tonight next year, ABC News is shifting a star resource from a hugely profitable morning show to a dying legacy newscast. All so she can sleep in a few hours later.

Matt Drudge broke the story: Charlie Gibson will retire as anchor of World News Tonight in January, at which point Sawyer, who has been co-anchor of Good Morning America since 1999, will take over.

Sawyer has long complained that she was tiring of the morning routine, and her tenure at GMA has been an open question for years. And Gibson, who was shabbily passed over in the wake of Peter Jennings' death from lung cancer and only got the gig because Bob Woodruff was injured in Iraq and Elizabeth Vargas got pregnant—a point he managed to make in his farewell memo, below—only hung around to gain the satisfaction of showing his bosses that the old horse still had some fight in him. So it's not terribly surprising that he would leave and Sawyer would take his slot. Still, it's a colossally stupid move. Or, as one TV insider put it to us: "It's the dumbest fucking idea in the long, hoary history of dumb fucking ideas in the news business."

Morning news is a growth business, and second-place GMA has been keeping Today on its toes for years. Sawyer is an integral part of a profitable, growing show, and ABC News has decided to upset the apple cart—putting GMA's success at risk and providing and opening to CBS to finally get in the game—so it can put her to work on an evening broadcast that nobody watches anymore outside of retirement homes. It's like trading a successful ballplayer down to the minor leagues.

Look how well it worked for Katie Couric: She gave up a successful morning franchise for the CBS Evening News, which has racked up little more than all-time audience lows since she took over. When CBS boss Les Moonves was engineering Couric's defection back in 2006, we asked him this question: If you could have Today's numbers at the CBS Early Show, or the NBC Nightly News' numbers at the CBS Evening News, which would you pick? He answered the only way a rational TV executive would: He'd pick the Early Show. Then why, we asked, are you devoting all your resources to resurrecting the Evening News? "Prestige," he answered. For some reason, these old people think a nightly newscast that grabs the biggest share of a dwindling and dying audience is something worth banging your dick on the table about.

Sawyer is apparently thinking along the same lines—she wants the Big Chair, even if it's not what it used to be. It'll be nice to have ladies helming two out of the three newscasts, and maybe Sawyer will be able to keep up the heated race with Brian Williams for the top slot that Gibson started. But to what end? So ABC News can lose ground on GMA, the show that actually brings in significant profits?

Here is David Westin's e-mail to ABC News staff, and below that is Gibson's note to World News Tonight staffers:

Today, Charlie Gibson announced to his colleagues at World News that he has decided to step down as anchor effective at the end of this year. I attach below Charlie's full email.

I have asked Diane Sawyer to serve as the next anchor of World News, and she will assume that position in January.

Charlie and I have been talking about his decision for several weeks, and he has persuaded me that this is both what he wants and what is best for him. I respect his decision, just as I respect the enormous contribution he has made to ABC News through the years. Most recently, he stepped in to lead World News after a difficult and turbulent time – both for the broadcast and for ABC News over all. We suffered from the loss of Peter and then the severe injuries to Bob. Charlie came to the fore to keep us on the path of doing the first rate journalism that had distinguished World News for many years. We owe him much for the leadership he gave us when we needed it most.

Since then, Charlie has covered all the major events with the substance and grace that we all expect from him. Most importantly, he headed our coverage during a presidential election unlike any other. Now, having accomplished so much in so many different parts of ABC News, Charlie has decided it is time for him to step down. I have told him that he has an open door to continue to work with ABC News, but he's asked for a bit of time before he comes back to us.

Diane Sawyer is the right person to succeed Charlie and build on what he has accomplished. She has an outstanding and varied career in television journalism, beginning with her role as a State Department correspondent and continuing at 60 Minutes, Primetime Live, and Good Morning America. She has interviewed every President since President George H. W. Bush up to and including President Obama. She has handled an array of breaking news special events, including on 9/11 and, most recently, the presidential election. She has done distinguished documentaries on topics as varied as North Korea, the plight of women in Afghanistan and in prisons here at home, and poverty in Camden, New Jersey, and in Appalachia. We are fortunate to have a journalist of Diane's proven ability and passion to step into the important position of anchor for World News. She will continue with her documentaries in her new role.

Diane's presence will certainly be missed on Good Morning America. But we are fortunate that both Charlie and Diane will remain with their current broadcasts for the next four months; we will be making further announcements well before any changes are made.

Charlie Gibson's e-mail to World News Tonight staff:

I have always been taught you should never bury the lead – so I write to tell you that I have told David Westin I want to step down as anchor of World News, and retire from full time employment at ABC News.

It has not been an easy decision to make. This has been my professional home for almost 35 years. And I love this news department, and all who work in it, to the depths of my soul.

I have received much comment, and quite a few emails and letters referring to the signoff Eddie Pinder convinced me to use - wishing that everyone has had a good day. But the proudest part for me has been saying "...for all of us at ABC News...", since those words signify in my mind that I have been in a position to speak for an entire news department that I consider second to none.

It had been my intention to step down from my job at Good Morning America in 2007 but with Peter's illness, Bob's injuries, and Elizabeth's pregnancy, the job at World News came open in May of 2006, and David asked me to step in as anchor. It was an honor to do so. The program is now operating at a very accelerated, but steady, cruising speed, and I think it is an opportune time for a transition – both for the broadcast and for me. Life is dynamic; it is not static.

I have told David I would like to continue in some capacity contributing occasionally to ABC News. He has been receptive to the idea – and we will be discussing what that role might be.

Most importantly, my heart is full of gratitude for those with whom I have had the privilege to work as a correspondent, as a host at Good Morning America, at Special Events, and now as anchor at World News.

I'll be anchoring World News through December and will have a chance to thank many of you personally. In the meantime let's get back to the news...