One of the Spanish reporters made the observation that prior to Madrid, Mourinho had been at big successful clubs, but not at the biggest clubs in their respective countries. So he was used to being able to turn the media on and off, and controlling his players and his dressing room partly by deciding which stories and rumours would go public and which ones would stay inside.
At Madrid he couldn't turn the media off. He'd come out screaming about something and get them into a feeding frenzy, then he'd try and calm it down by sending out Karanka to do the press conferences for the next month. Instead of calming it down it just meant that the cameras spent more hours chasing the players, the physios, even the trainers of his kid's football team etc and all the while the TV cameras were attempting to extract meaning from his body language in the dugout.
The British press will be grateful for his soundbites at the press conferences, but if he's not saying anything amusing or controversial he'll expect them to wander off to another story.
Incidentally a lot of the Spanish press think he wanted the United job, and that failing to understand the rules of being the centre of attention "all the time" was one of the reasons he didn't get it.