Sometimes we need to drastically change what we are doing. But we don't get support from management. For me this is the time to be disruptive. As co-owner of a small ISV we needed to be disruptive all the time. This was our only differentiator to bigger competition.
But in larger companies being disruptive is not that easy. It is not always possible to get management buy in. Even for ideas you think will change and improve the way you are working. This calls for stealth disruptive behavior.
Stealth disruptive behavior has helped people to introduce new successful techniques when upper management doesn't approve.
Time to use some history to explain my point. Lieutenant Donald Lewis (yes lieutenant, wikipedia is not always correct) was a radio expert. Using morse from an airplane he could spot where the bombshells dropped on the battlefield. This helped the artillery in the correct positioning of their pieces. Off course Donald Lewis did not get approval from the general staff. In stead of complying with policy he did it anyway. It turned out to be a big success and received wide adaptation.
Off course people take tremendous risks if you don't have buy in from management. It is dangerous to fail. But using lean/agile techniques we can minimize the failure and take small risks. When working in small increments we can see early on if something will fail or not and adjust en route.