Fer certainly does have some improving to do, but remember, he was in a struggling side, surrounded by inferior players not on his wavelength and it was his debut season in a new league and a new country, plenty of players need a season to adjust.
Fer, in my opinion is a complete midfielder, and this is because he has an even balance of attributes within his game. If you are going to say he isnt a complete midfielder you also need to state what you feel are the attributes he doesnt have? Fer can do everything, as opposed to our other midfielders who can only do something.
I dont disagree that Fer needed to improve, but in terms of ability he has got the lot