Then, you have to have the self-confidence and power to impose this will on the company's development team so it can work with you to realize your vision as soon as possible. As General MacArthur said, behind every lost battle are two words: too late. Can you see anyone but Marissa Mayer who fulfills either of these two criteria for Microsoft? But wait, there is more! Marissa Mayer is CEO of Yahoo!. It may seem like ancient history, but Microsoft did try to acquire Yahoo!. In an act of certified insanity by the previous management and board, Yahoo! rebuffed. It was one of the costlier acts of corporate self-delusion in history. Given the rise of Google, Facebook and even Twitter, it seems more urgent than ever to ensure that Microsoft can battle these players even on this newly expanded field of social interaction and commerce. In order to do so, Yahoo! of all companies comes the closest to having the remaining pieces of the puzzle Microsoft needs. Conclusion: Not only is Marissa Mayer the right person to re-invent Microsoft, but Yahoo! is as important for Microsoft's competitive matrix as it was when it bid for the company last time. There is just more thing: Enterprise versus consumer. Increasingly, enterprise technology is becoming more different than consumer technology. IBM ( IBM) realized this a decade ago, and sold its PC business to Lenovo. Dell ( DELL) got rid of its smartphone business. Cisco ( CSCO) shut down its consumer camera business, and divested Linksys. BlackBerry is now getting out of consumer in order to focus on enterprise. What it takes to run Microsoft's large enterprise business may be materially different than what it takes to run its consumer business. On the enterprise side, the interaction with the customers is very different. The marketing and PR is different. It's a different type of customer. If you're running for President, you have to decide if you're campaigning in front of the general population or if you're campaigning in front of the economics club at University of Chicago. This is to say that perhaps Microsoft has become too big, and it is almost impossible to have a new CEO optimize for both large enterprise and consumer markets. It might be necessary for Microsoft to divide into two companies. If so, Marissa Mayer may be better suited for the consumer half of the company. In either case, Alan Mulally isn't the ideal candidate for Microsoft, even though he may have been the ideal candidate for companies such as Ford and Boeing. On the other hand, if Marissa Mayer didn't exist, Microsoft would have to invent a Marissa Mayer in order to reinvent Microsoft's consumer business into something that can compete with Google, Apple, Amazon and Facebook. At the time of publication the author was long GOOG, AAPL and F. Follow @antonwahlmanThis article was written by an independent contributor, separate from TheStreet's regular news coverage.