This Vanity Fair interview with Bill Gates and Satya Nadella for their upcoming November issue does a good job capturing both men’s personalities and, even more importantly, offers a sense of the nature of the challenge facing Microsoft 2.0.

“The way I think about success is our relevance,” says Nadella.

Relevance, however, is exactly what Microsoft doesn’t have, according to its critics. “The Irrelevance of Microsoft” is actually the title of a blog post by an analyst named Benedict Evans, who works at the Silicon Valley venture-capital firm Andreessen Horowitz. On his blog, Evans pointed out that Microsoft’s share of all computing devices that we use to connect to the Internet, including P.C.’s, phones, and tablets, has plunged from 90 percent in 2009 to just around 20 percent today. This staggering drop occurred not because Microsoft lost ground in personal computers, on which its software still dominates, but rather because it has failed to adapt its products to smartphones, where all the growth is, and tablets. Even Microsoft’s new chairman of the board, a former IBM executive named John Thompson, told Fortune last winter that “there are some attributes to Microsoft today that do look vaguely like IBM circa 1990.” That is a particularly wounding comparison, because, as any tech person knows, IBM is the company that two decades ago an aggressive young Microsoft helped topple from the pinnacle of great technology companies.

The drop from 90% of all screens to 20% is both telling and subtle. That stat doesn’t take into account percentage of all data stored in Microsoft cloud solutions. Cloud is a perfect example of a business Microsoft originally missed, then pivoted to catch.