The Sando sacking caught everyone by surprise. He had done well in his first year, lost Tippett to a deal he didn't know about and Walker in his second, had done a reasonable job this season with injuries and had Crows looking competitive going forward.
McKenna dodged the bullet once before and the rumours have been going around for over 2 months that his head was on the chopping board.
Was heading for finals until the best player in the comp did a shoulder, so performance wise he was up there with Sando. The bolded bit is the most important though. That's the right way to sack a coach. None of this 'keep it in house' and make sure the coach is the first outside of the decision makers to know about it. You gotta leak it to your favourite 'journalists' so that everyone knows it's coming at least a couple of months in advance.
This new order at the Crows certainly has a lot of learning to do.