Stack ranking existed at MSFT before Ballmer became CEO, i.e., when billg was CEO.
It was a practice that Jack Welch brought into the corporate world and Microsoft was just guilty of following what were thought to be best practices at the time.
Source: worked at Microsoft before Windows Mobile was a thing.
As an aside, Windows Phone was my favorite phone OS and Ballmer seemed like the one who actually cared about it a lot.
Tangent:
I love that phrase. Anytime I hear someone make that statement I think about the 9,000 things that have been considered "best practice" until we actually understood that they weren't even "good practice". It gets thrown around as if it's been studied and confirmed when in reality it means "a bunch of people are doing it"