From a business point of view Ballmer did an excellent job. The company grew every year and was always one of the top tech companies. The same will probably happen to Apple (and Google) too. They magic touch goes away but they will be solid companies run by business people.
2000-2013 was pretty... frozen.
You don't need to remind of the failed battle of Mobile (that even Gates said it would give them at least 400b).
Also the Xbox One launch fiasco, Surface RT, etc. And of course, the longhorn... Which I don't think is a Ballmer problem exactly, but it happened.
