The culture of Cisco M&A is unlike anything seen in Silicon Valley.

Cisco actively encourages senior engineering employees to leave the company, start new ventures and return as leaders in the M&A process. It's not fair to compare Yahoo to Cisco when Cisco invests tremendous amounts of effort, time and money into these ventures to grow and nurture them (recent example: Meraki) until they can be reabsorbed into the Mothership.

Yahoo on the other hand is buying a bunch of companies that it knows only by reputation. Yahoo might be successful, but not for the same reasons that Cisco is successful. It's just a very different culture.

Exactly - some companies can pull off this kind of acquisition. It's entirely a corporate culture thing.