Nadella has made a few key changes, for example exempting internal product teams from having to consider Windows as the only OS to develop for, changed the incentive structure for sales to avoid pushing products enterprises didn't care about etc... When you're a CEO your success is usually not dependent by flashy all in decisions, especially if you're managing a giant company like MS. You are successful by setting policies that allow your talent to do more of the right stuff, your sales folks to sell more and better etc ...