Your article says that Google has overtaken Yandex in terms of the total usage for the traditional and mobile version of the Google website and its mobile apps (emphasis mine).
So a reasonable explanation is that Russians are increasingly using Google's apps: gmail, google calendar, the google now launcher; which probably has something to do with the fact that these apps come preinstalled on their phones. Not necessarily that they prefer Google for searching for Russian-language websites.
So a reasonable explanation is that Russians are increasingly using Google's apps: gmail, google calendar, the google now launcher; which probably has something to do with the fact that these apps come preinstalled on their phones. Not necessarily that they prefer Google for searching for Russian-language websites.