Microsoft’s next chief executive officer will need the expertise and strategic vision that can help the biggest software maker confront a broad range of threats that Steve Ballmer, for all his expertise as a salesman, was never able to repel. Microsoft, which supplies the software running most PCs, lost almost half its value on Ballmer’s watch. Microsoft requires a product person like Marissa Mayer, who oversaw some of Google’s most-popular services including its home page, and was brought in to turn around Yahoo, according to analysts and executive recruiters. The new CEO will also need to help Microsoft hone its strategy, comparable to Lou Gerstner’s overhaul of IBM. The challenge: making up for a lost decade when Microsoft fell behind Google and Apple in smartphones, tablets and Web search - and pushing it deeper into areas such as cloud computing, wearable technology and online advertising. Microsoft should look carefully within Google for possible successors.