Beats me why Yahoo's board selected Carol Bartz over Dan Rosensweig the last time around, but the mysterious decision-making group of the company's directors qualifies as the proverbial riddle, wrapped in a mystery, inside an enigma. Rosensweig understands media and the Internet better than most -- he's been doing Silicon Valley stuff since the late 1990s -- and nowadays he's Chegg's CEO. Full disclosure: He once was my boss at ZDNet, though I don't hold that against him. More important, he was Yahoo's COO between 2002 and 2007 and knows the company inside out. Would Yahoo be willing to go with someone so closely identified with ousted-CEO Terry Semel? That's the $64,000 question.