Silva is better but Mata is great. Remember Mata has help from Oscar and Hazard, Silva is in many games the only source of creativity so is targeted by our opponents who know that. If we had Silva, Oscar, and Hazard for example the other team would not focus so much on reducing Silva's space and freedom because there would be two other creative players who would need equal attention. It's a joke how few creative sources we have at this point and Silva suffers for that but make no mistake he is still a class player.