He was Microsoft's Cloud guy... the "services" part of their new "devices and services" thing. All about supporting Enterprise... in short, the part of Microsoft that's looking to not worry about competition with Apple (but perhaps with Google and Amazon), but not the part of Microsoft that most people recognize as Microsoft.
Maybe he's just their best guy. He's not a bad choice, politically... a tech company being run by an actual tech guy (or even a semi-tech guy, at least when he's Steve Jobs) resonates with the industry and individuals far more than a tech company run by a bean counter. But it's not just posturing. Look at all of the cool stuff Google does, being run by techies. Some of that fails, but it's also not their core business, so even failures don't look bad. Versus Microsoft, gambling and losing with Windows 8... and that, ironically, because they didn't listen to the techies. Microsoft just seems to be bad as doing new things... even the poorly designed Windows 8 stuff was a reaction to the mobile world MS had pretty much forgot about. Windows 8 was, after all, launched in 2012. That was the same year that Android became the first OS to outsell Windows as a consumer platform, basically since the first year or two of Windows.
On the other hand, this may also be Microsoft preparing for a consumer future in which Microsoft is just a bit player. Or even a sell-off of some or all of the consumer parts of Microsoft. The pundits have suggested selling off X-Box for quite some time (it's never made money), but you can't do that without changing the way Windows exists in the world, no matter how you do the split (since the current X-Box runs a custom version of Windows on an x86 processor).
