NBC Universal television boss Jeff Zucker got unexpected, and perhaps unwelcome, help last week in his plan to slash spending when his No. 2, Randy Falco, and Mr. Falco’s lieutenant David Zaslav defected from the company.

Mr. Zucker, in the middle of trimming 700 positions and $750 million in annual spending, lost Mr. Falco to Time Warner, where the executive will lead AOL. Mr. Zaslav, president of NBC Universal’s cable, domestic TV and new media distribution, abandoned the company for the top job at Discovery Networks.

Neither Mr. Falco, who was part of the NBC genome for more than 30 years, nor Mr. Zaslav, a 15-year veteran, are expected to be replaced. Instead, their duties will be parceled out to other executives. The company hasn’t decided which responsibilities will fall to whom, people familiar with the matter said.

Mr. Falco’s depature “will necessitate some changes in our leadership structure, and we will let you know those as soon as possible,” Mr. Zucker, CEO of NBC Universal’s TV group, said in an e-mail to employees.

“I am sad to lose a colleague that I—and many of us—have relied upon and enjoyed working with for so many years,” Mr. Zucker wrote. “Randy joined NBC straight out of college in 1975. Since then, he has had a hand in an incredible number of our most significant successes, across nearly every area of the company.”

Mr. Zucker’s tribute to Mr. Falco comes as NBCU tries to adjust to a decline in fortunes at its broadcast network and owned stations that has cost the company as much as $1 billion in advertising revenue and other income. The network is staging a comeback, ranking No. 3 season to date. Mr. Zucker decided to tackle the fiscal problems and retrofit the company at the same time under the plan he dubbed NBCU 2.0.

The departures of Mr. Falco and Mr. Zaslav will help trim payroll by several million dollars, people familiar with the matter said. Those savings, however, come with a cost measured in lost experience and more instability amid the most drastic cuts at the General Electric media company since the late 1990s, when Bob Wright, now CEO of NBC Universal, asked for 5 percent cutbacks for the second time since he was named president of NBC in 1986.

Mr. Zucker’s job cuts started two weeks ago at NBC News, which is a large target for cost reduction with its payroll of some 6,000 people. At “Dateline NBC,” about 17 people were forced out.

By the end of last week, the focus had shifted to “Today” and “NBC Nightly News,” where the total cuts are fewer than those suffered at “Dateline,” people familiar with the matter said. Up to 100jobs are being eliminated at Telemundo stations as job functions are centralized by region.

Within the NBC television stations group, three reporters of long standing were let go last week from WNBC-TV in New York, including medical reporter Max Gomez and the genial Jane Hansen, who has hosted the flagship station’s series of successful local specials.

The stations had been leaving positions empty for months in a strategy to save as much as possible by attrition and voluntary early retirements and buyouts, a person familiar with the matter said.

At every level so far, the number of volunteers for buyouts or early retirement is described as exceeding expectations, which may mean less blood will have to be shed. NBC executives and spokespeople declined to give numbers on how many employees have exited voluntarily. A close observer, who declined to be identified, said that savings already accounted for, along with an upturn in the finances at the company and its various divisions, may allow a softening of the cuts built into the NBCU 2.0 initiative.