The specific technologies that were successful is irrelevant. Microsoft has and continues to invest in nearly every computer related technology that may come around the corner or they got late on.
The problem with Microsoft was everything went through Windows. The entire company was designed to promote Windows.
This was the fundamental flaw with Microsoft that Nadella changed. He quickly not just made Windows just another part of Microsoft’s business, to a great extent he actively devalued it.
The fact that Ballmer invested in Azure, etc before Nadella would all be irrelevant because under Ballmer Azure would have remained a red headed step child to Windows, so it’s unlikely to have seen much success under him anyways. Same goes for pretty much everything else Microsoft is doing right now.