In a surprising about face, Eileen O’Neill, recently named global group president at Discovery Studios, has announced she is instead leaving the company.

In August, Discovery Communications president and CEO David Zaslav named the well-respected O’Neill who had been head of Discovery Channel, and who also had overseen the growth of  TLC,  to the new post of Global Group President at Discovery Studios in one of those executive shakeups for which Zaslav is so well known, and which do so much to keep Discovery staffers on their toes.

O’Neill, a 25-year Discovery exec, was assigned to lead its worldwide production division, overseeing all international facilities and creative talent at Discovery Studios, managing the company’s in-house production units and serving on the board of directors of All3Media once that transaction closed, the company announced back then.

Two months later, Zaslav named former Walt Disney Studios Chairman Rich Ross to replace O’Neill as President of Discovery Channel. Ross joined Discovery Communications last month, based at the company’s L.A. office, and began shaking things up at the channel.

O’Neill was taking time off before making her switch to Discovery Studio.  This morning she instead said in a memo to staff:
I want you to know, effective May 1, 2015, I will no longer be at Discovery Communications. The date is significant as it marks my 25th anniversary with this truly amazing company (not including the four months of unpaid internship labor that preceded my hiring date!).

I realize not everyone will miss my emoticon-laced memos, sent at all times of the night and day, but I know I will miss you guys.  Through incredible successes, and not a few nail-biting challenges, we always delivered as a team.

In making the announcement about her move to Discovery Studios back in August, Zaslav had called her “one of the very best we have at Discovery.”

In her memo, O’Neill looked back at her time as an exec at Discovery Communications:

Together, we still hold the highest prime delivery this century of any reality show on all major ad-supported cable networks for W25-54 (4.1M) and W18-49 (4.6M)  (Jon and Kate); we introduced a sweet baker and a couple of fast and loud car guys to our global audiences; we celebrated five more births with Jim and Michelle Duggar since we first met them in 2004; we held hands and held our collective breath watching Felix Baumgartner ascend to Emmy-winning heights and Nik Wallenda power-walk across the Grand Canyon and into history; we cheered as Prince William and Kate said “I Do” to our global audiences Live; we said prayers for and with our talent (both crew and on-air characters) as they ventured to some of the harshest locations around the world, some never to return; one dark September day, some of us huddled with colleagues and strangers in offices, waiting for an all clear signal that it was safe to leave One Discovery Place; we kept audiences hooked on chopper builders and gold seekers; we took risks to find the first images of a giant squid and we crashed a 727 airplane for the sake of aviation safety; we found a little couple big on heart and a medium full of love; we never shied from controversy whether it was with Muslims in Michigan, Sarah in Alaska or Amish folk in places which surprised; and, of course, we unleashed mega sharks (and a seal named Snuffy) for record-breaking Shark Weeks.

No word how O’Neill’s exit will affect Discovery Studio and how Zaslav might restructure things — again. In eight months O’Neill has been on a break before she was scheduled to begin her new gig, Ross has come in like a whirling dervish. One day last month he made a strong statement about the direction in which he’s taking Discovery Channel, naming HBO veteran John Hoffman as Executive Vice President of Documentaries and Specials. (This month, Hoffman announced Discovery had picked up domestic and international rights to the documentary Racing Extinction, from Louie Psihoyos, the Oscar-winning director of The Cove, which had its world premiere January 24 at the Sundance Film Festival.)

The same day he announced his hire of Hoffman, Ross appeared before skeptical TV critics at Winter TV Press Tour 2015 and announced he would not continue to air the network’s ratings-grabbing tongue-in-cheek mockumentaries. Ross noted they had brought enormous ratings, and new viewers, to Discovery Channel but said he thought the programming genre had run its course.

Critics came ready to do battle with the new programming chief over Discovery’s mockumentary Megalodon: The New Evidence —  the highest rated telecast of Discovery Channel’s most recent Shark Week, with 4.8 million viewers. So excited did they become with Ross’s response, they started asking him if he’d kill programs they don’t like that don’t even air on Discovery Channel.