there isn't one. google's momentum in taking marketshare hasn't diminished one bit. yahoo has less share in ad dollars then they did two years ago. there really isn't much a new ceo can do to reverse that.
from a shareholder perspective, the msft deal was a no-brainer. especially at today's trading range. yhoo isn't going back to the 34 msft offered them anytime in the next five years. the next ceo will do their best to get something going again