At no point did I say he was a super sub in fairness. We will need a lot of players next season being in four competitions, and having Rashford, Martial,Ibra and mkhy is fantastic. But, we do need more options beyond them, if we sold Mata your only subs are pretty much Rooney, Depay and Januzaj. That's not enough if we want to stay in the cup competitions for a long time and do well in the league.
I'm not sure I agree with this idea that Mata is a player that needs the team tailored to him. It simply not true. Mata can quite easily not start every game for us next season and still do well for us because he's a very good footballer.