The main two reasons behind chelsea's success in the last two seasons has been because of the facts that they have a system and they have big stars,every person in the team knows what his role is, and because of Mourinho's strategy of placing two players for every position, has brought competition within the team and evidently so because Drogba ever since the arrival of Shevchenko from AC Milan is literally playing out of his skin and Lampard after having a disappointing outing at Germany is out there proving his worth, Mourinho backs his players from time to time.