If Juan Mata wants to re-break into this Chelsea squad as a first-choice player, he's unlikely to do it as Oscar's expense, says Jose Mourinho. According to the manager, he intends to build the club around the Brazilian, using him as the Blues' primary playmaker:
In this moment, Oscar is my No. 10 and, if somebody tells me that Oscar is not Chelsea’s best player since the beginning of the season, I’d have to disagree. These are football issues.
It's a fair enough comment. Mourinho goes on to elaborate:
[Mata and Oscar can play together], when [Mata] adapts to it. But I’m not ready to play Oscar following full-backs [ed - i.e. as a winger], because he plays in that position for the country with more talented players than anyone else in the world in that position. I want to build with Oscar as my No. 10. I want the other two players, from the side, to adapt to that reality and learn now to do things that they were not ready to do before.
I don't think it's quite fair of the manager to insinuate that Mata has to adapt and do things he wasn't 'ready' to do before. Mata played as a wide player in both Andre Villas-Boas' 4-3-3 and Roberto di Matteo's 4-2-3-1, and the best football of the latter's tenure came with Mata on the right and Oscar in the middle. Granted, it was unbalanced, but Mata's already put in plenty of hard work as a wide man.
But this isn't all about Mata. It shouldn't be, at least. Oscar's really coming into his own these days, and he's a player with almost limitless potential. Watching him grow (and Mourinho's definitely encouraging that) is going to be one of the true joys of being a Chelsea supporter over the coming years.