I think people have some unfair/unrealistic expectations from Mata. On the one hand they want him to create and score a-plenty like he did for Chelsea, he did have 8 goals in 10 games at one point, but that wasn't enough. Then his defending is criticised (despite his size, speed and it not being natural to him) then when he does defend well, it goes unnoticed or is dismissed.
I think the price tag raises some expectations and some fans expect him to perform almost like Ronaldo or Messi on a weekly basis. He has been in and out of the side, hasn't really had a settled position (like many of our players this year) and is pretty much knocked whenever he plays. The fact is he is not playing for Chelsea, nor is he always in his favoured or best position, yet he still manages to score and set up goals and at the same time always has a smile on his face and something positive to say after games. He is not a complainer or trouble maker and he seems to be universally liked throughout the team.
Anyone else also notice that RvP seems to have his best games when Mata and Herrera are playing?
The lad is class both on and off the pitch and I think not only does he deserve his chance and his place in the team, he deserves a break from some of the more critical fans.