MS is not agile in the same sense as your YC funded startup is. That would be comparing speedboats to super tankers and in the world of super tankers Microsoft is one of the super tankerest of them all.
Nokia, RIM, Boeing, HP, Yahoo and many others couldn't pull a single "pivot" out of the hat all the while Microsoft keeps on dancing.
They are far from my favorite companies, however Microsoft and IBM prove year by year that elephants can and do dance. And what a gracious waltz that is. For an elephant of course.