Chelsea don't have to worry about getting to the knockout rounds of the Champions League. Like the other English sides bar Arsenal (who merely have to avoid losing 3-0 to Rafa Benitez's Napoli to make it through), the Blues have secured passage from the group stages with a game to spare. Now the real concern is navigating those group stages, and given performances like we saw in Basel, observers are right to be skeptical about their ability to do that.
Part of the problem on Tuesday was the inability to rotate the midfield. Jose Mourinho opted for a 4-3-3, and he had three midfielders available -- the same trio who played three days before at Upton Park. They were duly overrun by Basel. In truth, there wasn't much choice in who he played centrally. It's probably the most demanding position on the pitch, but the Blues only had four players registered there, and one of them is out with a long-term injury.
At least one small step will be made to rectify that problem come the new year:
I will change Marco van Ginkel with Essien in the Champions League squad list. We are going to try to find balances. Our squad is our squad. Instead of thinking about the market, we will think about trying to work and trying to improve the team
This isn't a major change, of course (and it would be much better if we just had van Ginkel back!) but having a functional midfielder we can spell the rest with means less chance of playing with an utterly exhausted core. I don't think Michael Essien's inclusion is enough, but it's something. Having him registered would have helped this week, at least.