HBO CEO Richard Plepler announced his resignation yesterday, less than a year after AT&T completed its acquisition of HBO and the rest of Time Warner Inc.

In a company-wide memo available in this Hollywood Reporter story, Plepler told employees that he made the "difficult decision" to leave at "an inflection point in the life of this wonderful company."

Plepler worked at HBO for nearly 28 years, serving as chairman and CEO since 2013 and as co-president from 2007 to 2013. He struck a positive tone in his memo. "Thanks to all of you, we are today churning on all cylinders both creatively and as a business," he wrote. "Thanks to all of you, I can move on to the next chapter of my life knowing that the best team in the industry remains here to carry on our continued progress and success."

But "Plepler found he had less autonomy after the merger, according to two people familiar with his thinking," The New York Times reported.

Other reports cited the same problem. As CNBC wrote:

According to people familiar with the matter, this is an issue of autonomy. Plepler wanted to run HBO, and new WarnerMedia CEO John Stankey, an AT&T veteran, was effectively running HBO. Plepler had ideas about technology and international expansion that didn't jibe with Stankey's vision, according to a person familiar with the matter. The two are also "different people" and didn't have the closest relationship, another person said. So after six years of running HBO autonomously, Plepler told Stankey earlier this month he wanted to leave, two of the people said.

Turner President David Levy is also leaving the company, and he announced his decision in an internal memo that said he's "ready for a professional change," CNN reported.

AT&T seeks big changes

HBO has succeeded for decades by producing a limited number of high-quality shows. But shortly after AT&T completed its purchase of Time Warner in June 2018, the new owner told HBO employees at a town hall-style meeting that the network wasn't making enough money. HBO needed more content to keep viewers' attention for hours every day and to get "more data and information" about customers, Stankey told HBO employees at that meeting. Stankey warned employees that they would face "a tough year," and they would need to do "a lot of work to alter and change direction a little bit."

Changes sought by AT&T seem to be geared toward making HBO a bit more like Netflix, the biggest streaming video provider.

"Plepler and [HBO] entertainment president Casey Bloys had brushed off suggestions that HBO would need to up its content tally, modest in comparison to Netflix's, but all that changed when [AT&T division] WarnerMedia was formed," the Hollywood Reporter article said. "The network is now looking to ramp up its original offerings in an effort to stay competitive with Netflix, Amazon, and umpteen other upcoming streaming rivals."

AT&T CEO Randall Stephenson, speaking about HBO parent WarnerMedia and its "creative imagination," told The Wall Street Journal last year that "you need to guard that culture with your life." But Stephenson also said that "the business model does have to change," and that it would be a "very difficult migration," the Journal wrote.

Plepler's departure came days after a federal appeals court upheld AT&T's acquisition of Time Warner, dealing a blow to the Justice Department's attempt to reverse the merger.