Well, past executives and directors have put Yahoo into a corner so hiring Mayer is a massive pivot. If she succeeds, she will become the biggest tech hero since Steve Jobs. If not, then nothing to lose given the direction that Yahoo has been heading (or not!).
Yahoo's board is so naive, she is a good follower, icing for your cake, not the main dish can drive the change.
she is stupid enough to accept this position, well, 13 years's good luck blinded her. she is going to become another carly fiorina.
Did Yahoo feel it needs Googles DNA to survive the crisis or does it think a fresh face will give it a much needed makeup?
If they can answer one question, they would know where they are and where they are going - "What does Yahoo stand for in the world of internet"
IMO Yahoo has turned out to be the Motorola of online business world.