It was difficult to include Juan Mata in this list because: a) he's an exceptionally gifted footballer, and b) he is not having a great time of it at Stamford Bridge under Jose Mourinho.
However, when Mata has featured for the Blues this term he has often been disappointing - a shadow of the player who has performed so brilliantly for the west London outfit over the last two seasons.
Mata simply must start performing better to earn the No. 10 spot back from Oscar, who continues to impress, despite the uncertainty of not knowing how Mourinho perceives him as a footballer.
Failure to do so will leave Mata firmly stuck to the Blues' substitutes' bench.