Meanwhile, the challenge for Stelter, a media reporter at The New York Times with pit-bull reporter instincts and a snark-infused, twitchy, Twitter-­generation writing style uneasily applied to long-form journalism, is to make a book-length narrative out of how NBC slipped and ABC gained. A 27-year-old industry savant of endless energy and reportorial resourcefulness (he started his influential media blog, TVNewser, as a college student), Stelter certainly works his web (and Web) of sources feverishly. He hangs out in control rooms. He snoops and digs. He regurgitates Nielsen ratings. He also loads “Top of the Morning” with a slapdash accretion of details, asides and glib pop-cultural references better suited to his snappy tweets (I’m a follower), a stream of chatter that doesn’t distinguish between the trivial and the valuable. One example of the former: “Curry, as you may not be surprised to hear, was the kind of student who protested when the university proposed to close the library at midnight rather than leave it open all night.” Another: the onetime NBC honcho Dick Ebersol was wrong about the short-lived “Today” host Deborah Norville “the way Liza Minnelli was wrong about David Gest, the way AOL was wrong about Time Warner.” (Small point of order from this Time Inc. alumna, but wasn’t Time Warner even more wrong about AOL?) And one more: the former “GMA” executive producer Ben Sherwood “probably likes classical music and stuff.” That’s cold.

Step around the clutter, and in the end Stelter has two relatively brief stories to tell. The first is the downer saga of how, with ratings starting to erode at “Today,” executives decided early in 2012 that Ann Curry’s performance was part of the problem, that she and Matt Lauer did not exude good chemistry — those executives were right! — and that it was time to move Curry out of the seat occupied over the years by Meredith Vieira, Katie Couric and Jane Pauley, among others, to be replaced by a new Female Person. (Did these suits not see the brilliant-because-true 1987 comedy classic “Broadcast News”? Firings happen all the time.)

Unfortunately, those same executives did a phenomenally clumsy job of implementing the succession, which, Stelter takes pride in reporting, gained the in-house, covert-op nickname Operation Bambi. Curry wept on TV, viewers blamed Lauer for forcing her out (as well as for making a girl cry), and those same viewers expressed their displeasure by switching to “GMA,” where that family appeared to be much nicer and seemed to be having more fun. (That Curry is no defenseless baby deer but rather an experienced adult with as much ego as the next millionaire shall go undiscussed here, except for Stelter’s aside: “Curry, by this point, would have to have been as dumb as a second-hour morning show segment not to have realized that something was up with her employment situation.”)

The second brief story is a warm, uplifting one about love and goodness and care and compassion in the midst of personal crisis, and also about cutthroat competition. “GMA” owes a sizable percentage of its current success under the command of the hard-charging Ben Sherwood, now the president of ABC News, to the warmth and all-for-the-team graciousness of Robin Roberts, a former ESPN anchor who was promoted to “GMA” co-host in 2005, sitting beside the show saviors then, Diane Sawyer and Charles Gibson. And in the way of family lore, viewers know that Roberts ran to find her kin in Biloxi, Miss., right after Hurricane Katrina; that she had surgery for breast cancer in 2007; that she conducted the scoop interview with President Obama in 2012 in which he declared his support for gay marriage; that her mother died right before Roberts went on medical leave for a bone-marrow transplant to treat a life-threatening blood disorder in August 2012; and that she rallied enough to return to work in February 2013.