Not the biggest fan of it, especially at the start of the season, but right at this moment I can't really complain too much either. At the end of the day, this time last season and the season before, we were out of the title race. This year we're 2 points behind and getting better, Hazard is coming into some good form, as is Willian, while Oscar seems to have hit his stride again after a dip in form and an injury. As awesome as Mata is I think we were too dependent on him the last 2 years, now it's a little more spread out. If he could hit form during the game time he gets then he'd give Mourinho no reason to drop him, but unfortunately he's doing nothing to merit a spot in the team due to a loss in confidence, and no matter how many starts he's been getting he hasn't performed like we know he can. He hasn't exactly been bad, but with other guys in form waiting to get on the pitch, he'll always be the first hooked, the Southampton game is a perfect example.
So yeah, pretty much, as much of a fan of him as I am, I can't say he should be in the team based on current form. It's not a nice situation but Mourinho's decision has so far been justified. Everyone would have assumed at the start of the season that we'd be worse off not having Mata as a first choice player, but look, we're a half decent bet to win the title and starting to look stronger.