Miguel Delaney with a great piece on José Mourinho at ESPN FC:
That double-sided approach has a deeper effect over the course of the season. Those around the Chelsea team say Mourinho will use it to “play games” with his squad, especially those players he doesn’t fully know. He will criticise them at moments they don’t expect, or suddenly drop them at moments they don’t expect.
The intention, however, is not to just manipulatively keep them on edge, but also to test them, to see whether they are mentally strong. That helps explain the ruthlessly forensic way Mourinho has so deeply changed his squad over the past two years. Of the 18-man squad involved in his first game back, the 2-0 win over Hull in August 2013, 11 are now gone.
That approach also gradually lifts the competitive baseline of the squad by simple conditioning, setting ever high standards.