I don't know about Carly when she was at HP, would hardly call that successful. The 25 billion purchase of compaq in 2002 might be one of the biggest blunders of all time.
As for MM, she's a winner. You can feel the winds shifting as soon as she took the helm. Yahoo is a buyout target because MM is captain and people like her. The talent will follow her and its only a matter of time before yahoo is a force to be reckon with. There's a lot of work to be done but I see her team executing their goals year after year. Buyout or no buyout yahoo stock is a bargain at these levels.