I have no evidence to back this up, but I suspect more and more developers are moving to Symfony2 due to the glacial pace of Yii development.<p>Yii v1.1 was released in January 2010. In the following 3.5 years, there have been many changes in the world of web development - namespacing and traits in PHP, AWS-style hosting going mainstream, JavaScript MVC frameworks - and Yii neither takes advantage of them, nor makes it easy for you to take advantage of them.<p>It's a shame, but unless they have some revolutionary idea, Yii is probably dead in the water.