I think it is crazy to say Yahoo was a sinking ship unable to be made buoyant. The number one thing they have going for them is Name/Legacy Habit. People still yahoo just because they still do. You could have let 90% off the company go, destroyed all the technology (but not the data, always import it into the new systems to not alienate long term customers) and started over.

Instead she decided she wanted to be a newspaper/tv channel, instead of a tech company. Look at the trajectory Medium.com has taken, or wordpress, even atavist. Vox Chorus and Gawker Kinja. Instead yahoo chose to continue to compete with about.com as a crappy content mill / 2nd layer newswire.

Yahoo Fantasy and Yahoo Finance and Yahoo Messenger and Flickr were all basically left to die. There was really no reason NOT to clone FBMessenger/Line/WeChat/QQ/WhatsApp. They should have been adding features to Finance and Messenger every week.