Open sourcing the C# compiler represents a fair amount of effort (code cleansing, IP review, license selection/compliance checking, etc) -- likely more work than could be completed in Nadella's short tenure. Therefore, it is likely that the compiler had been prepared, and his actions represent the long standing desires of the technical staff that were ignored/denied by Ballmer. Ditto goes for the iPad version of Office. As such, I wouldn't say these moves represent Nadella's changing the company, as much as him ending Ballmer's repression.