A discussion with, among others, guys from Knight Ridder who justify why they broke URLs during a recent redesign. Pointing to the lousy performance of your competitors and explaining that you're on par with them is not something I would bet my credibility on.

As I pointed out, I don't think KR handled their redesign properly, but as Shelley Powers wrote in this thread:

"However, all of this pre-supposes a third business decision - that it was worthwhile for KR to go to possibly extraordinary means to do this mapping [of old to new URLs], and build in this functionality. It is legitimate for KR to make a business decision that the costs of doing this aren't justified by the loss of business, customer satisfaction, revenue, whatever."