Cech to Arsenal is understandable. He asked to stay in England and obvious was good enough to play for the top teams. United has De Gea so and City at the time were happy with Hart. That basically left two teams, Arsenal and Spurs. Spurs have always trusted Lloris and Arsenal were very interested so the deal was sensible.
It's true some teams have a director who makes the transfers and other teams give full control to the manager. I believe the manager should hold 90% of the power unless the team has a very sound strategy sich as Southampton were they sign players based on an analysis and profile. Even their manager is selected based on that.
Well this confirms my suspicions that at least half of the transfers weren't up to Mourinho . You might say don't take his word for it but I want you to look at the transfers and see if those were Mourinho like players and type players that Mourinho would let go especially to direct rivals . Like Cech and Mata .
http://www.bbc.com/sport/football/37501563