One of the under-appreciated reasons great technology companies fall is that once they hit a certain size, talented employees who have risen through the company's ranks begin leaving for younger, more dynamic companies with longer runways for growth. 

While Google (Nasdaq: GOOG) still ranks atop many lists for best employers, its size-and the inherent bureaucracy that comes along with it-is a major challenge to keeping talent. The most recent illustration of this is that Hugo Barra is leaving the company to join Chinese smartphone upstart Xiaomi. His exit comes just six months after Android chief Andy Rubin left the company. 

While there might have been unique personnel issues behind Barra's departure (reports cited a recent break-up with an employee now dating Google co-founder Sergey Brin), his departure to a Chinese start-up is interesting on its own. Yet, it becomes even more fascinating when you consider Xiaomi heavily forks Android, ripping out key Google services like its app store. 

Xiaomi is definitely a fascinating company, data from smartphone research companies showed it outselling Apple (Nasdaq: AAPL) last quarter. To hear more about the troubles of big tech companies retaining talent and why Barra might be interested in moving on to a company many call the "Apple of China," watch the video below. 

Eric Bleeker, CFA has no position in any stocks mentioned. Jamal Carnette owns shares of Apple. Simon Erickson owns shares of Apple. The Motley Fool recommends Apple and Google. The Motley Fool owns shares of Apple and Google. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.