A big shareholder in Yahoo is asking for a leadership change at the beleaguered company.

In a letter to Yahoo's board, CEO Marissa Mayer and Chairman Maynard Webb, Starboard Value LP criticized the company's performance over the past three years, saying that the management team hired to turn around the core business has "failed to produce acceptable results."

Mayer became CEO of Yahoo Inc. in 2012 and Maynard Webb became chairman in 2013.

Starboard said that if a change is not made, an election may be needed to replace some members of the board.

Starboard said it thinks Yahoo can improve the performance of the core business and separate its assets, but that it will require a change in leadership and strategy.