In the video above, Lloyd Grove and Brian Stelter dissect the transition at ABC News - David Muir in for Diane Sawyer on "World News," George Stephanopoulos as chief anchor for the whole network - and what it says about the future of the “star” newscaster.

Stelter said:

You've heard the story that ABC is telling about this big transition. Diane Sawyer wants to step down, ABC says, from "World News" to focus on big interviews and specials. So David Muir will take over in September, although frankly, it's sort of already taken over. Sawyer was on vacation all this week, so he was filling in.

And as for George Stephanopoulos, well, ABC's story is that he was not passed over for the top job. Rather, he will be the chief anchor for the whole network, coming in whenever there is big breaking news.

So, that's ABC's story, but I don't believe it, and neither do a number of my most reliable sources at ABC. For example, here's a big question that they are asking - why isn't Diane being guaranteed a certain number of primetime special each year, or being given her own production unit like Ann Curry got after being booted from the "Today" show?

Grove said Sawyer has "done very well for ABC News - she's beat Brian Williams in the all-important 25 to 54 age demo on which advertising is sold." About the transition, he said, "If they brought it up first, I'm sure she agreed, and if she agreed, I'm sure it was with a lot of sweeteners and her new gig is going to be pretty wonderful for her, I would suspect."

Stelter and Grove also discussed the relationship between Muir and Stephanopoulos:

STELTER: Is there a rivalry, do you think, forming? Because my sense from the last ten days has been there's been a camp for George and there's a camp for David - each of them saying different things about how involved the other guy is going to be.

GROVE: I don't think there's a personal rivalry, at least not yet between George and David, certainly not the kind of personal rivalry as between Diane and Barbara Walters, but definitely the camps are working it hard. I mean, I've had heard from both camps myself, they think - the Muir camp thinks that George's role has been exaggerated in the press and, you know, George's camp thinks that, yes, I'm the lead anchor, or, he's the lead anchor.

In the video above, Zeynep Tufekci and Tal Yarkoni discuss the controversial Facebook research that altered the content of users’ newsfeeds, and the power of Facebook more generally.

In this week's Red News/Blue News, Brian Stelter breaks down liberal and conservative media reaction to this week’s Supreme Court decision in the Hobby Lobby case - was it a victory for religious liberty or an infringement on women’s rights?