Days before the Alibaba Group controversy got resolved, Bartz delivered another bad-news whammy during the company's second-quarter earnings call: Yahoo's U.S. display ad business, consistently a strong point for the company, had stumbled badly.

Bartz blamed the problem on a reorganization of the U.S. display ad team conducted in May, which she said resulted in a higher-than-expected turnover of employees, that led to the sales slowdown.

She said weak U.S. display ad sales would continue during the third quarter, before picking up in the fourth quarter, when the new staffers would be fully settled in.

Yet, this may have been the last drop for Yahoo's board of directors, who let Bartz go on Tuesday, although her contract didn't expire until January 2013.

As recently as June, Board Chairman Roy Bostock publicly expressed his confidence in Bartz, when at an investors' meeting he addressed rumors that she was going to be fired.