If the defeat against Basel can be pinned on anything in particular, Jose Mourinho thinks it's on player fitness:
I felt the team was tired. They paid the price of the international break and a crucial match against West Ham. There was no reaction from the players, and wrong decisions. I am not sad with them, as I understand they were not fresh.
Maybe I should have made more changes, but after playing so well against West Ham, there was the temptation to play the same team. We should get a better result than this. But I do not blame the players.
It's a pretty good explanation, as explanations go; there was only one change made from the West Ham game. Chelsea played superbly in that one and not so superbly this time, with the duo of Frank Lampard and Oscar in particular fading from standouts to anonymity.
Mourinho wasn't using freshness as an excuse, though. He's the one who gets to determine how fresh the players are, and with the size of his squad he should have done far better with keeping the likes of Oscar rested. If Chelsea are tired, it's his fault. But there's one area in which Mourinho didn't have much choice but to do with tired legs, and that's in midfield.
This is where Marco van Ginkel's injury really comes back to bite us. Rather than being cover at every midfield position, van Ginkel's on the treatment table with torn knee ligaments, and that means that we don't have a viable replacement for, say, Frank Lampard in the 4-3-3. Without that cover, we're forced into playing guys on short rest, and sometimes that's not going to work out well for 35-year-olds.
This is a compelling reason to stay away from 4-3-3 for the moment. We have more attacking players than we know what to do with, but in the centre we have four players really capable of doing a job (five if we include David Luiz, which we probably shouldn't). I'd trust John Obi Mikel to be able to play twice a week, and Ramires could probably do more than that, but Michael Essien and Frank Lampard simply don't seem capable of shouldering that burden. Using a two-man pivot will keep everyone fresher until we can rectify the problem in January*.
*Unless it's Lampard and Ramires all the time, which... yeah.
If only van Ginkel was healthy. More flexibility, less leaning on Lampard in the middle, happier days all around.