Chelsea have a ridiculous array of attacking midfielders. We were already well stocked with Juan Mata, Eden Hazard, Oscar and Victor Moses; now Kevin de Bruyne and Andre Schurrle have been added to the mix. In general, having too much talent is never a bad thing, but juggling the egos of elite players is difficult enough without having to worry about getting everyone enough playing time in a World Cup year.
Fortunately, heading into the season it doesn't sound like there's much fear of neglect. At least from Andre Schurrle:
There are no promises. I want to train hard and then help the team with my qualities. In every big club there is competition and that's what I wanted. I have this competition in the national team where there are also many good players in my position.
There are so many matches that everyone will play. We need everyone, so I don't think there is a risk. For so long in this national team we have had so many great players and such a good team. I see no risk for me. I know my qualities, I know what I can do.
The first sentence of the second paragraph is the important piece here. Chelsea play an absurd number of games every season, and the likes of Mata and Oscar were suffering from overuse last year. If Mourinho can get everyone working for the team and accepting that they won't be playing every minute of every game, which should be easy enough when the matches start coming in thick and fast, we're in good shape.
That said, it's easy not to worry about playing time before the season's even started. The real test will come when Schurrle's been sat on the bench for a couple of weeks and Joachim Loew starts telling him he needs to be out on the pitch to get to Brazil with Germany next summer. I'm not sure he'll be so cavalier about the strong competition he faces for playing time then...