I've noticed one thing
-Hazard plays much better if Mata is beside him
I think Mourinho does want to play Mata, but the problem is that Mourinho doesn't trust any of his his central midfield options enough so that we can go all out attack in a game and play Mata each and every time. I'm guessing we're looking at a defensive/central midfielder in January, who can pass the ball forward confidently and quickly with bags of stamina. We don't have that in one player and if Mourinho can find that type of player in January, we may well see Mata play more so that Mata doesn't have to track back,
Mourinho's concern is that our central midfield doesn't protect the back 4 well enough like Makelele used to do, or Ballack after Makelele left so he's asking other midfield players to do this dirty work to compensate, which will consequently mean our attacking players are a little less sharp going forward IMO