I've worked with many managers who enter a new organization and hit the ground running. They set new targets, launch programs, and challenge the stats quo. These are leaders who, until this point, have been successful in challenging environments. This time, rather than achieving the success they're used to, their efforts are met with resistance. Fast forward a few months, and little has been achieved.
What happened is that cultures clashed. The tools and behaviors that they developed in other organizations don't always transfer well.
There are two scenarios here.
Some organizations, especially those with a successful legacy, are defined by their culture. When Tim Cook took over Apple, he had to acknowledge the culture that Steve Jobs put in place before gradually introducing change. When Ron Johnson took over as CEO of J.C. Penney, the Apple culture didn't transfer well, and he had to leave.
In other cases, an organization's culture is the cause of its decline. Even then, it cannot simply be ignored. In an organ transplant, the doctor first has to remove the bad organ before putting in the healthy one. The same is true here, and care must be taken to understand the existing culture. Only then can a plan be made to change it and to make the change stick.