I often found the opposite can be be true, people can, for decades on end, be totally ignorant of what happens next door. When you show them the effect of their ignorance you often get something akin to the stages of grief. Definitely the anger, and with you in particular. The, 'I don't care whose fault it is, I'm not here to apportion blame' line only goes so far, especially since other managers and even the CEO might be very interested in apportioning blame. At least they are allies for the change that needs to happen