2) No true number 10s
Chelsea’s great transfer businesses has been built on the sales they’ve made. Last January they sold Juan Mata and Kevin de Bruyne for large fees, and were able to bring in Nemanja Matic, who they needed much more, in return.
Those deals were irresistible, especially for those sums, but it has left Chelsea with a dearth of playmakers. Oscar plays there now, but there are no alternatives to the Brazilian. If he gets injured, or drastically loses form (as he did just 12 months ago), Mourinho’s only option is to play Cesc Fabregas in the hole. And who was the only replacement for Fabregas in midfield? Oscar.