Starboard in a letter to the board of directors implied that Mayer and her officers needed to go, without naming her specifically. “To be successful, dramatically different thinking is required, together with significant changes across all aspects of the business starting at the board level, and including executive leadership,” Starboard CEO Jeffrey Smith said in the letter on Wednesday. Starboard, which owns about 0.75 percent of Yahoo, has been pushing for changes at the Internet company since 2014, urging it to separate its Asian assets and auction off the core business.