If Change Is A Constant, Why Do Most Transformations Fail?

We know how important business transformation is in consulting circles - it's on everyone's lips and every 10K filling. Considering how much change happens around us, it seems it would be a natural state of being, and yet, most times it's just a failure. Why is it so hard to transform when change is the norm? Note: apologies for Shann's audio track, it seems something went a little wrong during the recording!