They have children close in ages. They and their families vacationed together on the maiden voyage of the Disney cruise ship Fantasy, and shared several trips to Walt Disney World.

Mr. Staggs had every reason to believe he was on track to succeed Mr. Iger. During the year since Mr. Staggs was named to the No. 2 position, Disney had moved from one triumph to another: an Oscar for the revived animation unit’s “Big Hero 6”; lavish praise and box office success for Pixar’s “Inside Out;” vindication of the Marvel acquisition with another smash “Avengers” hit; the record-setting opening of “Star Wars: The Force Awakens.”

And then there is Disney’s most ambitious project of all: the imminent unveiling of its $5.5 billion Shanghai Disneyland resort, Mr. Staggs’s major achievement as theme park chairman. In the year that Mr. Staggs was chief operating officer, first-quarter earnings jumped 36 percent to a record $2.9 billion.

True, Disney’s stock price, along with market averages, was down. After peaking at over $120 in August, it was trading this week at just under $100. But that decline was set off by Mr. Iger’s comments to analysts that growth at the Disney-owned sports network ESPN was slowing under subscriber losses. Until then, Disney had been the best-performing stock in the Dow Jones industrial average for 2015.

Mr. Iger also appeared to be laying the groundwork for his own next act: to lead the National Football League’s return to Los Angeles after a 21-year absence. Mr. Iger was granted options to buy minority stakes in the Raiders and Chargers and was named chairman of a holding company that would move the teams to Los Angeles and oversee the building of a new stadium and adjacent real estate development.

Mr. Iger met with N.F.L. owners in Houston in January to pitch the deal. According to a detailed account in the Disney-owned ESPN the Magazine, Mr. Iger’s legendary charm fell flat with the league owners, who opted for a rival bid on Jan. 12. Mr. Iger’s franchise options were terminated.